Explore the core architecture of the operating system, including the kernel, memory management, and process scheduling.

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Core OS Resources
General: DevForums subtopic: App & System Services > Core OS Core OS is a catch-all subtopic for low-level APIs that don’t fall into one of these more specific areas: Processes & Concurrency Resources Files and Storage Resources Networking Resources Network Extension Resources Security Resources Virtualization Resources Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"
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Aug ’25
App with shallow depth entitlement not appearing in Auto-Launch > When Submerged
I'm building a freediving app for Apple Watch Ultra using the shallow depth entitlement (com.apple.developer.submerged-shallow-depth-and-pressure). My app uses WKExtendedRuntimeSession with the underwater-depth background mode, and it works correctly — the session starts, Water Lock activates automatically, and Crown hold water ejection ends the session as expected. However, the app does not appear in Settings > General > Auto-Launch > When Submerged on the watch. Other third-party apps (including one that hasn't been updated in ~2 years and presumably only has the shallow entitlement) do appear in this list. My configuration: WKBackgroundModes: ["underwater-depth", "workout-processing"] WKSupportsAutomaticDepthLaunch: true (Boolean, in watch app Info.plist) Entitlement verified in both the signed binary and provisioning profile watchOS 26.3, Apple Watch Ultra 2 Tested with: development build, TestFlight, and direct Xcode deploy. Watch restarted after each. The app does not appear in any case. The documentation at https://developer.apple.com/documentation/coremotion/accessing-submersion-data states: "Adding the underwater-depth Background Mode capability also adds your app to the list of apps that the system can autolaunch when the wearer submerges the watch." Does auto-depth-launch require the full depth entitlement (com.apple.developer.submerged-depth-and-pressure), or should the shallow entitlement be sufficient? Is there an additional step required for the app to appear in the When Submerged list? Any guidance appreciated.
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nobrowse mount option ignored?
Shouldn't it be supported? Also is there a way to disable spotlight indexing on a mounted folder? mds_stores is going wild on fskit volumes. mount -o nobrowse -t passthrough ~/Downloads ~/mnt alexf@MacBook-Pro-3 build % mount file:///Users/alexf/Downloads/ on /Users/alexf/mnt (passthrough, local, nodev, nosuid, noowners, noatime, fskit, mounted by alexf)```
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System-wide deadlock in removexattr from revisiond / APFS
System-wide deadlock in removexattr from revisiond / APFS We're experiencing a deadlock on certains systems when our software is installed, which is causing side effects in our process (and likely others) such as blocked queues and increased memory usage. According to the spindump, revisiond appears to be holding an exclusive lock within the kernel. Process: revisiond [426] UUID: 5E9B9E04-984B-31AD-A4FF-A1A90B7D53A1 Path: /System/Library/PrivateFrameworks/GenerationalStorage.framework/Versions/A/Support/revisiond Codesigning ID: com.apple.revisiond Shared Cache: 25AE5A2A-FE2A-3998-8D4E-F3C5C6E6CEB6 slid base address 0x189834000, slide 0x9834000 (System Primary) Architecture: arm64e Parent: launchd [1] UID: 0 Sudden Term: Tracked Memory Limit: 50MB Jetsam Priority: 40 Footprint: 6225 KB Time Since Fork: 1740319s Num samples: 940 (1-940) Num threads: 5 Note: 1 idle work queue thread omitted [...] Thread 0xc0616d 940 samples (1-940) priority 46 (base 4) last ran 241692.754s ago 940 start_wqthread + 8 (libsystem_pthread.dylib + 7068) [0x189d0ab9c] 940 _pthread_wqthread + 292 (libsystem_pthread.dylib + 11852) [0x189d0be4c] 940 _dispatch_workloop_worker_thread + 692 (libdispatch.dylib + 85356) [0x189b65d6c] 940 _dispatch_root_queue_drain_deferred_wlh + 292 (libdispatch.dylib + 87156) [0x189b66474] 940 _dispatch_lane_invoke + 440 (libdispatch.dylib + 45048) [0x189b5bff8] 940 _dispatch_lane_serial_drain + 944 (libdispatch.dylib + 42420) [0x189b5b5b4] 940 _dispatch_client_callout + 16 (libdispatch.dylib + 113364) [0x189b6cad4] 940 _dispatch_call_block_and_release + 32 (libdispatch.dylib + 7004) [0x189b52b5c] 940 ??? (revisiond + 168768) [0x10494d340] 940 ??? (revisiond + 165940) [0x10494c834] 940 ??? (revisiond + 40264) [0x10492dd48] 940 ??? (revisiond + 56680) [0x104931d68] 940 <patched truncated backtrace> 940 removexattr + 8 (libsystem_kernel.dylib + 23768) [0x189cd1cd8] *940 ??? (kernel.release.t6000 + 15240) [0xfffffe000886fb88] *940 ??? (kernel.release.t6000 + 1886348) [0xfffffe0008a3888c] *940 ??? (kernel.release.t6000 + 7730436) [0xfffffe0008fcb504] *940 ??? (kernel.release.t6000 + 2759592) [0xfffffe0008b0dba8] *940 ??? (kernel.release.t6000 + 2808244) [0xfffffe0008b199b4] *940 apfs_vnop_removexattr + 1044 (apfs + 474512) [0xfffffe000be8d4d0] *940 decmpfs_cnode_set_vnode_state + 80 (kernel.release.t6000 + 2945816) [0xfffffe0008b3b318] *940 IORWLockWrite + 184 (kernel.release.t6000 + 496184) [0xfffffe00088e5238] *940 ??? (kernel.release.t6000 + 494624) [0xfffffe00088e4c20] *940 ??? (kernel.release.t6000 + 619452) [0xfffffe00089033bc] *940 ??? (kernel.release.t6000 + 624472) [0xfffffe0008904758] The bulk of the other processes are waiting for that lock. (suspended, blocked by krwlock for reading owned by revisiond [426] thread 0xc0616d) (blocked by krwlock for writing owned by revisiond [426] thread 0xc0616d) Around the time of the event, these messages were logged by revision: 2026-03-06 18:49:37.781673-0500 0x16b7 Error 0x7f92f364 426 14 revisiond: [com.apple.revisiond:default] [ERROR] CSCopyChunkIDsForToken failed for 41639 2026-03-06 18:49:37.781716-0500 0x16b7 Error 0x7f92f365 426 14 revisiond: [com.apple.revisiond:default] [ERROR] updateEntry for new entry <private> failed 2026-03-06 18:49:37.781738-0500 0x16b7 Error 0x7f92f366 426 14 revisiond: [com.apple.revisiond:default] [ERROR] no entry for '<private>' 2026-03-06 18:49:37.781754-0500 0x16b7 Error 0x7f92f367 426 14 revisiond: [com.apple.revisiond:default] [ERROR] failed assembleInfoForOffset for fsid 16777234 fileid 359684022 offset 0 size 14334 (path <private>) Our agent uses Endpoint Security Framework to monitor events, and provide anti-tamper functionality for installed components and processes. While several EndpointSecurity calls appear in the spindump stack traces, we don't have any evidence that any calls from revisiond were blocked. What we'd really like to to understand what that lock is (appears to be decompressing an object on an APFS volume), what revisiond and APFS are doing with it, and what might cause it to deadlock. Of note, one of our processes is also waiting on that lock, one thread for reading and the other for writing. This issue affects machines running several macOS versions (15.x, 26.x). The machine in the examples is running macOS 26.3 (25D125)
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Can a third-party DriverKit HID dext seize raw HID reports from an external mouse via a top case–related path?
We are trying to determine whether a third-party DriverKit HID dext can seize or intercept raw HID input reports from an external mouse through any top case–related path in the HID stack. Our dext is based on IOUserHIDEventDriver, and the goal is to receive raw input reports before they are translated into higher-level pointer events. Apple’s public HIDDriverKit documentation describes IOUserHIDEventDriver as the driver object responsible for dispatching pointer, digitizer, scrolling, and related HID-originated events, but it is not clear to us whether any “top case” path is actually exposed or supported for third-party matching in DriverKit. What we want to clarify is specifically about external mouse devices, not the built-in trackpad itself. Questions: Is there any officially supported way for a third-party DriverKit HID dext to bind through a top case–related path and receive raw HID input reports from an external mouse? Is “top case” something that third-party DriverKit drivers can meaningfully target for matching/attachment, or is it only an internal Apple implementation detail? If such a path exists, can it be used to seize raw reports before they are converted into higher-level pointer events? If not, what is the officially supported boundary for third-party DriverKit access to raw reports from external mouse-class HID devices? To be clear, we are not asking about synthesizing pointer events. We are asking whether a third-party DriverKit dext can directly observe or seize the original HID input reports from an external mouse by attaching through any top case–related portion of the HID stack. If “top case” is not a public DriverKit concept that third parties can target, confirmation of that would also be very helpful.
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DriverKit Access to Built-In MacBook Trackpad Raw HID Reports
We are trying to intercept raw reports from the built-in MacBook haptic trackpad using a DriverKit IOUserHIDEventDriver dext. Our dext installs and activates successfully: OSSystemExtensionRequest finishes with result 0 systemextensionsctl list shows the dext as activated enabled the dext is embedded correctly in the app bundle However, it never attaches to the built-in trackpad IOHIDInterface. ioreg shows the built-in trackpad interface still matched only by Apple’s HID dext. We also observed that Apple’s own HID dext appears to use com.apple.developer.driverkit.builtin, while that entitlement is not available in our provisioning profile. Our dext specifically relies on: IOUserHIDEventDriver::handleReport(...) SetProperties() with kIOHIDEventDriverHandlesReport Questions: Is com.apple.developer.driverkit.builtin required for a third-party IOUserHIDEventDriver to match a built-in internal trackpad IOHIDInterface? Is that entitlement public/requestable, or Apple-internal only? At what stage is it enforced: activation, personality matching, provider attach, or before Start()? If builtin is not available to third parties, is there any officially supported way to receive raw reports from the built-in MacBook trackpad in DriverKit? Our conclusion so far is that activation succeeds, but provider binding to the built-in trackpad fails due to built-in-only authorization/matching.
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Sporadic crash in xzm_main_malloc_zone_init_range_groups when spawning large binaries (macOS 26.3.1)
We're seeing a sporadic crash (~2-3% of spawns) when launching a large Mach-O binary via posix_spawn(). The crash happens inside libsystem_malloc.dylib during __malloc_init, before any application code runs. The process never reaches main(). Environment: macOS 26.3.1 (25D2128), Apple Silicon (ARM64) Crash signature BUG IN LIBMALLOC: pointer range initial reservation failed, Abort Cause 3 #0 libsystem_malloc.dylib: xzm_main_malloc_zone_init_range_groups.cold.1 #1 libsystem_malloc.dylib: xzm_main_malloc_zone_init_range_groups #2 libsystem_malloc.dylib: xzm_main_malloc_zone_create #3 libsystem_malloc.dylib: __malloc_init #4 libSystem.B.dylib: libSystem_initializer #5 dyld: dyld4::Loader::findAndRunAllInitializers The binary It's a Chromium component-build test binary (browser_tests): ~1.5 GiB on disk, 5.54 GiB total VA footprint (__TEXT 517 MiB, __LINKEDIT 1.04 GiB, __PAGEZERO 4 GiB) Links 527 dylibs via @rpath All images span ~16.4 GiB of VA when loaded A simple loop that spawns this binary 200 times via posix_spawn() reliably shows 2-5 crashes. Spawning /bin/cat 1000 times produces zero failures. Investigation We did extensive analysis to understand the root cause: ASLR is irrelevant. We disabled ASLR using _POSIX_SPAWN_DISABLE_ASLR (flag 0x0100) and the failure rate is unchanged (~2% with or without). With ASLR disabled, the library addresses are identical across all crashes, confirming the VA layout itself isn't the problem. Plenty of free VA space is available. We compared the memory layout of crashing processes (from crash reports) with successful ones (via vmmap): In successful spawns, XZone places its MALLOC zones (SMALL, LARGE, metadata) in the large free regions after the loaded dylibs — for example at 0x784400000 and 0xD32000000, with 13-22 GiB contiguous free gaps available. In crashing processes, the same free regions exist (the image layout is identical), but xzm_main_malloc_zone_init_range_groups fails to reserve into them. Based on libmalloc/tests/memory_pressure.c, XZone needs 8 GiB for pointer ranges and 10 GiB for data ranges. The free gaps after the dylibs are far larger than this, yet the reservation sporadically fails. No workarounds exist. MallocNanoZone=0 has no effect (the crash is before zone configuration). The crash is entirely within system code. Questions Is this a known issue in XZone malloc on macOS 26.x? Is there any environment variable or entitlement that could work around this? Any guidance on what makes xzm_main_malloc_zone_init_range_groups fail non-deterministically when contiguous VA space is clearly available?
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Safari iOS 17 layout issue
Safari on iOS 17, when entering characters into text input box after deleting characters, the layout is off. Here's the HTML: <body> <div id="J001" style="display: inline-block;"> <div id="J001__0" style="display: inline-block;"> <input id="J001__0__input" style="display: inline-block; height: 28px; padding:2px; border:1px solid gray;"></div> <div id="J003__0" style="display: inline-block;"> <button id="J003__0__btn" style="display: inline-block; height:34px;">a</button> </div> </div> </body> Enter "A" into text input box. Delete "A" with the backspace(x). Enter "A" into text input box, the button position will be shifted down. iOS 17 の Safari にて、テキスト入力ボックスで文字を削除した後、文字を入力するとレイアウトが崩れます。 テキスト入力ボックスに「A」と入力します。 バックスペース(x)で「A」を削除します。 テキスト入力ボックスに「A」と入力すると、ボタンの位置が下にずれます。
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17h
My macOS app is unable to read a Managed Preferences plist unless the App Sandbox is disabled. Is there any solution to read the MDM plist file while the sandbox is still enabled?
I created two sample apps — one sandboxed and one non‑sandboxed. I tested reading Managed Preferences using bash commands, CFPreferencesCopyValue for a domain, and defaults read. Everything works correctly only when the sandbox is disabled in the entitlements. When the sandbox is enabled, I’m unable to read values from /Library/Managed Preferences/. Is there any supported way for a sandboxed macOS app to read an MDM-delivered preference plist under /Library/Managed Preferences/? Any guidance on the correct and Apple‑supported method would be appreciated.
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Crashes occur on iOS 26.4
Since updating the OS to 26.4, the app has been crashing more often after I launch it. The devices on which this issue has been confirmed are as follows: ・iPhone SE (2nd generation) ・9th-generation iPad ・8th-generation iPad ・5th-generation iPad mini We have confirmed that the application functions properly on all devices prior to the OS update.
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AccessorySetupKit: Can I use bluetoothNameSubstring be used without bluetoothCompanyIdentifier?
I'm integrating AccessorySetupKit for BLE earbuds discovery and running into an issue with ASDiscoveryDescriptor configuration. Our earbuds don't have a fixed Bluetooth SIG company identifier. So I'm trying to use bluetoothNameSubstring + bluetoothServiceUUID instead. However, this combination never discovers any devices. The picker appears but stays empty. As soon as I add a bluetoothCompanyIdentifier, the device is found instantly. I reproduced this with my Bose QC35 II as well, so it's not specific to our hardware. My configuration: bluetoothServiceUUID: set to our custom UUID bluetoothNameSubstring: set to a substring matching the advertised device name NSAccessorySetupBluetoothServices + NSAccessorySetupBluetoothNames both set in Info.plist supportedOptions: .bluetoothPairingLE iOS 26.3.1, iPhone 11 The documentation doesn't mention that bluetoothCompanyIdentifier is required. Is bluetoothCompanyIdentifier actually required for BLE discovery? If so, is there a recommended approach for devices that don't have a fixed company identifier?
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How to modify the launchctl config to start Postfix?
On Sequoia, I want to configure my postfix as a server. And for this I have to change the way postfix is started from: /System/Library/LaunchDaemons/com.apple.postfix.master.plist But this file is on the read only / file system. Then I just unloaded this startup, and made a new one in: /Library/LaunchDaemons/com.apple.postfix.master.plist and I was able to start it. But on the next system boot, the system one in /System/Library/LaunchDaemons was started again. How should I cleanly and permanently achieve this server basic modification?
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26.4 beta and RC versions are unable to be created on anything but 26.4 beta host OS
We're trying to create 26.4 beta and RC VMs on 15.x and 26.3 host OS' without success. We see Tue Mar 17 17:27:36 40 anka.log (install) 45803: failed to install macOS: Error Domain=VZErrorDomain Code=10006 "Installation requires a software update." UserInfo={NSLocalizedFailure=A software update is required to complete the installation., NSLocalizedFailureReason=Installation requires a software update.} Yet, if we create it the same way on 26.4 beta host OS, it works. We've tried the usual tricks of installing latest Xcode and preparing it (accepting license, etc). But, they don't work on 26.3 and 15.x. What's the trick to get the creation of 26.4 to work on <= 26.3 host OS?
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Custom icons for folder aliases not showing
Problem: custom icons for folder aliases not showing System drive and external drive custom alias folder icons don't showup on desktop or external drive (OS14.6 Sonoma 2023); they only show-up as plain folders or with an odd document icon. Alias doesn't connect to image; however it's there, easily accessible via spacebar. Finder doesn't save the custom icon to the alias. See below for workaround. Summary: I have custom alias icons on my desktop linking to their source files on the system drive and external drive.. however they do not display the custom icon. After upgrading from OS10.14 Mojave to OS14.6 Sonoma 2023, system drive & external drive custom alias icons no longer display the icon on either drive (there is a work-around for Mojave; see history section). Personal impact: hampered file navigation and workflow; I'm lost, can't tell where anything is; not having my icons makes it especially difficult to navigate my files and hampers my workflow significantly. Desired outcome: all custom icons for folder aliases linking to source files (on system & external drives) appear on the desktop, and in all directories on system & external drives (including encrypted external drives). Status.. August 2024: called apple support, they said there is no solution, and there are no plans to fix it, and no plans for a fix in OS 15 Sequoia (in public beta now) Action: ❯ leave feedback at https://www.apple.com/feedback/macos/ ❯ join this campaign to fix this once and for all! -- After 20 years of dealing with this issue.. we need to fix this. History: ▪ OS 10.14 Mojave 2018: external drive alias icons don't work; because upon startup, the icon images for these files disappear; because when system starts it loads the system drive icons but not the external drive icons because it's password protected, hence icon information does not get loaded; alias icons can't connect with unmounted external drive @ boot; however it's there, easily accessible via spacebar the FIX: alias the icons on the desktop each time after boot, however the names are altered ▪ OS X 10.11 El Cap 2015: drag the icons to a folder then back to desktop.. sometimes this works I stayed on OS9 as long as possible because of the OS10 icon problem ▪ OS 9: all custom alias folder icons worked fine Givens: space bar has fast access to icon -highlight alias and press space bar -- seems that it would be a simple solution, since the image is there -- get info for alias also has the image in preview How to make a custom icon: open a pic (typically from a screenshot; .png), select image with cursor with shift key down (for a perfect square), copy ⌘C, click target folder, get info ⌘I, click on folder icon on top left corner, paste ⌘V Fix -- How? --make a solution approach for a macOS dev? some bash process to link to icon; how to access icon Swift? process to renew the alias icon process goes through all desktop icons.. fixes them; new icon, correct name routine where all icons on desktop link to their files easily making a new alias.. as easy as making a regular alias; cammand L, etc make alias search for the image app that makes alias create custom desktop.. a GUI w links -- INTERIM FIX / WORKAROUND create a new folder on your desktop, name it, place it's alias inside the folder, fix the icon, when you open the desktop folder, you will then have to click on the alias --this is very time-consuming and tedious note: there may be easier options for OSs prior to Sonoma; review History section workflow: symbol note: ⇧ shift, ⌃ control, ⌥ option, ⌘ cammand create new folder on desktop ⌘⇧N , name it.. if the name is already taken by the alias, change the alias's name; for example.. alias it ⌘^A click on this new folder then ⌘I (get info) click on the alias, open source location ⌘R (or ⌘⌥^A on older OSs), click on source file (if not highlighted) then ⌘I (get info) , click on folder icon on top left corner, copy ⌘C click on the get-info window you opened for the new folder, click on folder icon on top left corner, paste ⌘V (if not working see ¹ below), close each of these windows with ⌘W place the associated aliased folder into the new folder you can also do this in groups of folders (3-6 seems is optimal).. for example.. move 3 alias icons to clear area on desktop, create 3 new folders and place them below the aliases, select all aliases and ⌘C, open a text document and ⌘V, fix names & name new folders, select new folders, ⌘I, select target aliases, ⌘R, ⌘I for each, move the alias windows below the new folder windows, copy/paste icons from source to new file, close these windows, place alias folders into new folders ¹ if paste function not working.. move on to the next folder and come back.. it can be moody, if it's not working at all.. restart the computer note2: some icons now have a yellow streak at the bottom let us know if you have any solutions or workarounds, or can code this (provide a script or app)
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Cellular not initializing on iPadOS 26.4 (resolved by network reset)
We are seeing an issue after updating iPads to iPadOS 26.4 where cellular service is lost until network settings are reset. Environment: Devices managed via Apple Business Manager and Microsoft Intune Carrier: Verizon Confirmed affected devices: iPad (9th generation) eSIM Behavior: After update, device shows no cellular service No prompt to re-activate or re-add the cellular plan The plan appears to still be present on the device Workaround observed: Resetting Network Settings restores service Notes: This does not appear to be a provisioning issue (no need to re-add eSIM) Behavior suggests the cellular/eSIM state may not be initializing correctly after update Toggling Cellular or Airplane mode has not yet been tested for service restoration. We have not yet confirmed whether devices using a physical SIM are affected Still gathering data on scope across additional iPad models Additional observation: We have not observed this behavior on iPhones (e.g., iPhone 16 on iOS 26.4 with LTE remains unaffected) Has anyone else observed similar behavior on iPadOS 26.4, particularly on managed devices or eSIM configurations?
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copyfile Sometimes Fails to copy .DS_Store when Copying a Folder But Does Not Report Usable Error
Testing copyfile on a folder on an external volume (which takes a bit a of time) I'm running into an issue where copyfile gets to the end of the operation and then just fails. In the callback I can see that the failure occurs on a .DS_Store file inside the folder. So for a .DS_Store it is simple enough for me to just ignore the error and return COPYFILE_SKIP but the somewhat more concerning issue here is that the true error reason is seemingly not reported? In the callback if I read errno it is 0. When copyfile returns it returns -1 after I return COPYFILE_QUIT (and errno is 0) so I don't know what the error is or the appropriate way to handle it. For .DS_Store just skipping seems reasonable but when copying a folder it may be appropriate to get the true failure reason. But checking the last path component of source path seems like a hack way to handle errors. If a file in the copying folder with important user data I can't just silently skip it - it isn't clear to me how I should properly proceed in a situation where I can't get the actual reason for the failure.
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Core OS Resources
General: DevForums subtopic: App & System Services > Core OS Core OS is a catch-all subtopic for low-level APIs that don’t fall into one of these more specific areas: Processes & Concurrency Resources Files and Storage Resources Networking Resources Network Extension Resources Security Resources Virtualization Resources Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"
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0
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0
Views
639
Activity
Aug ’25
App with shallow depth entitlement not appearing in Auto-Launch > When Submerged
I'm building a freediving app for Apple Watch Ultra using the shallow depth entitlement (com.apple.developer.submerged-shallow-depth-and-pressure). My app uses WKExtendedRuntimeSession with the underwater-depth background mode, and it works correctly — the session starts, Water Lock activates automatically, and Crown hold water ejection ends the session as expected. However, the app does not appear in Settings > General > Auto-Launch > When Submerged on the watch. Other third-party apps (including one that hasn't been updated in ~2 years and presumably only has the shallow entitlement) do appear in this list. My configuration: WKBackgroundModes: ["underwater-depth", "workout-processing"] WKSupportsAutomaticDepthLaunch: true (Boolean, in watch app Info.plist) Entitlement verified in both the signed binary and provisioning profile watchOS 26.3, Apple Watch Ultra 2 Tested with: development build, TestFlight, and direct Xcode deploy. Watch restarted after each. The app does not appear in any case. The documentation at https://developer.apple.com/documentation/coremotion/accessing-submersion-data states: "Adding the underwater-depth Background Mode capability also adds your app to the list of apps that the system can autolaunch when the wearer submerges the watch." Does auto-depth-launch require the full depth entitlement (com.apple.developer.submerged-depth-and-pressure), or should the shallow entitlement be sufficient? Is there an additional step required for the app to appear in the When Submerged list? Any guidance appreciated.
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43
Activity
6h
Bootable ssd
Hi all my apologies for being a little inexperienced. how do I install Tahoe 26.5 on an external SSD? I have downloaded the .IPSW but it won't instal. Dev
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23
Activity
9h
nobrowse mount option ignored?
Shouldn't it be supported? Also is there a way to disable spotlight indexing on a mounted folder? mds_stores is going wild on fskit volumes. mount -o nobrowse -t passthrough ~/Downloads ~/mnt alexf@MacBook-Pro-3 build % mount file:///Users/alexf/Downloads/ on /Users/alexf/mnt (passthrough, local, nodev, nosuid, noowners, noatime, fskit, mounted by alexf)```
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40
Activity
10h
System-wide deadlock in removexattr from revisiond / APFS
System-wide deadlock in removexattr from revisiond / APFS We're experiencing a deadlock on certains systems when our software is installed, which is causing side effects in our process (and likely others) such as blocked queues and increased memory usage. According to the spindump, revisiond appears to be holding an exclusive lock within the kernel. Process: revisiond [426] UUID: 5E9B9E04-984B-31AD-A4FF-A1A90B7D53A1 Path: /System/Library/PrivateFrameworks/GenerationalStorage.framework/Versions/A/Support/revisiond Codesigning ID: com.apple.revisiond Shared Cache: 25AE5A2A-FE2A-3998-8D4E-F3C5C6E6CEB6 slid base address 0x189834000, slide 0x9834000 (System Primary) Architecture: arm64e Parent: launchd [1] UID: 0 Sudden Term: Tracked Memory Limit: 50MB Jetsam Priority: 40 Footprint: 6225 KB Time Since Fork: 1740319s Num samples: 940 (1-940) Num threads: 5 Note: 1 idle work queue thread omitted [...] Thread 0xc0616d 940 samples (1-940) priority 46 (base 4) last ran 241692.754s ago 940 start_wqthread + 8 (libsystem_pthread.dylib + 7068) [0x189d0ab9c] 940 _pthread_wqthread + 292 (libsystem_pthread.dylib + 11852) [0x189d0be4c] 940 _dispatch_workloop_worker_thread + 692 (libdispatch.dylib + 85356) [0x189b65d6c] 940 _dispatch_root_queue_drain_deferred_wlh + 292 (libdispatch.dylib + 87156) [0x189b66474] 940 _dispatch_lane_invoke + 440 (libdispatch.dylib + 45048) [0x189b5bff8] 940 _dispatch_lane_serial_drain + 944 (libdispatch.dylib + 42420) [0x189b5b5b4] 940 _dispatch_client_callout + 16 (libdispatch.dylib + 113364) [0x189b6cad4] 940 _dispatch_call_block_and_release + 32 (libdispatch.dylib + 7004) [0x189b52b5c] 940 ??? (revisiond + 168768) [0x10494d340] 940 ??? (revisiond + 165940) [0x10494c834] 940 ??? (revisiond + 40264) [0x10492dd48] 940 ??? (revisiond + 56680) [0x104931d68] 940 <patched truncated backtrace> 940 removexattr + 8 (libsystem_kernel.dylib + 23768) [0x189cd1cd8] *940 ??? (kernel.release.t6000 + 15240) [0xfffffe000886fb88] *940 ??? (kernel.release.t6000 + 1886348) [0xfffffe0008a3888c] *940 ??? (kernel.release.t6000 + 7730436) [0xfffffe0008fcb504] *940 ??? (kernel.release.t6000 + 2759592) [0xfffffe0008b0dba8] *940 ??? (kernel.release.t6000 + 2808244) [0xfffffe0008b199b4] *940 apfs_vnop_removexattr + 1044 (apfs + 474512) [0xfffffe000be8d4d0] *940 decmpfs_cnode_set_vnode_state + 80 (kernel.release.t6000 + 2945816) [0xfffffe0008b3b318] *940 IORWLockWrite + 184 (kernel.release.t6000 + 496184) [0xfffffe00088e5238] *940 ??? (kernel.release.t6000 + 494624) [0xfffffe00088e4c20] *940 ??? (kernel.release.t6000 + 619452) [0xfffffe00089033bc] *940 ??? (kernel.release.t6000 + 624472) [0xfffffe0008904758] The bulk of the other processes are waiting for that lock. (suspended, blocked by krwlock for reading owned by revisiond [426] thread 0xc0616d) (blocked by krwlock for writing owned by revisiond [426] thread 0xc0616d) Around the time of the event, these messages were logged by revision: 2026-03-06 18:49:37.781673-0500 0x16b7 Error 0x7f92f364 426 14 revisiond: [com.apple.revisiond:default] [ERROR] CSCopyChunkIDsForToken failed for 41639 2026-03-06 18:49:37.781716-0500 0x16b7 Error 0x7f92f365 426 14 revisiond: [com.apple.revisiond:default] [ERROR] updateEntry for new entry <private> failed 2026-03-06 18:49:37.781738-0500 0x16b7 Error 0x7f92f366 426 14 revisiond: [com.apple.revisiond:default] [ERROR] no entry for '<private>' 2026-03-06 18:49:37.781754-0500 0x16b7 Error 0x7f92f367 426 14 revisiond: [com.apple.revisiond:default] [ERROR] failed assembleInfoForOffset for fsid 16777234 fileid 359684022 offset 0 size 14334 (path <private>) Our agent uses Endpoint Security Framework to monitor events, and provide anti-tamper functionality for installed components and processes. While several EndpointSecurity calls appear in the spindump stack traces, we don't have any evidence that any calls from revisiond were blocked. What we'd really like to to understand what that lock is (appears to be decompressing an object on an APFS volume), what revisiond and APFS are doing with it, and what might cause it to deadlock. Of note, one of our processes is also waiting on that lock, one thread for reading and the other for writing. This issue affects machines running several macOS versions (15.x, 26.x). The machine in the examples is running macOS 26.3 (25D125)
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484
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11h
Can a third-party DriverKit HID dext seize raw HID reports from an external mouse via a top case–related path?
We are trying to determine whether a third-party DriverKit HID dext can seize or intercept raw HID input reports from an external mouse through any top case–related path in the HID stack. Our dext is based on IOUserHIDEventDriver, and the goal is to receive raw input reports before they are translated into higher-level pointer events. Apple’s public HIDDriverKit documentation describes IOUserHIDEventDriver as the driver object responsible for dispatching pointer, digitizer, scrolling, and related HID-originated events, but it is not clear to us whether any “top case” path is actually exposed or supported for third-party matching in DriverKit. What we want to clarify is specifically about external mouse devices, not the built-in trackpad itself. Questions: Is there any officially supported way for a third-party DriverKit HID dext to bind through a top case–related path and receive raw HID input reports from an external mouse? Is “top case” something that third-party DriverKit drivers can meaningfully target for matching/attachment, or is it only an internal Apple implementation detail? If such a path exists, can it be used to seize raw reports before they are converted into higher-level pointer events? If not, what is the officially supported boundary for third-party DriverKit access to raw reports from external mouse-class HID devices? To be clear, we are not asking about synthesizing pointer events. We are asking whether a third-party DriverKit dext can directly observe or seize the original HID input reports from an external mouse by attaching through any top case–related portion of the HID stack. If “top case” is not a public DriverKit concept that third parties can target, confirmation of that would also be very helpful.
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71
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11h
DriverKit Access to Built-In MacBook Trackpad Raw HID Reports
We are trying to intercept raw reports from the built-in MacBook haptic trackpad using a DriverKit IOUserHIDEventDriver dext. Our dext installs and activates successfully: OSSystemExtensionRequest finishes with result 0 systemextensionsctl list shows the dext as activated enabled the dext is embedded correctly in the app bundle However, it never attaches to the built-in trackpad IOHIDInterface. ioreg shows the built-in trackpad interface still matched only by Apple’s HID dext. We also observed that Apple’s own HID dext appears to use com.apple.developer.driverkit.builtin, while that entitlement is not available in our provisioning profile. Our dext specifically relies on: IOUserHIDEventDriver::handleReport(...) SetProperties() with kIOHIDEventDriverHandlesReport Questions: Is com.apple.developer.driverkit.builtin required for a third-party IOUserHIDEventDriver to match a built-in internal trackpad IOHIDInterface? Is that entitlement public/requestable, or Apple-internal only? At what stage is it enforced: activation, personality matching, provider attach, or before Start()? If builtin is not available to third parties, is there any officially supported way to receive raw reports from the built-in MacBook trackpad in DriverKit? Our conclusion so far is that activation succeeds, but provider binding to the built-in trackpad fails due to built-in-only authorization/matching.
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4
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224
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12h
Sporadic crash in xzm_main_malloc_zone_init_range_groups when spawning large binaries (macOS 26.3.1)
We're seeing a sporadic crash (~2-3% of spawns) when launching a large Mach-O binary via posix_spawn(). The crash happens inside libsystem_malloc.dylib during __malloc_init, before any application code runs. The process never reaches main(). Environment: macOS 26.3.1 (25D2128), Apple Silicon (ARM64) Crash signature BUG IN LIBMALLOC: pointer range initial reservation failed, Abort Cause 3 #0 libsystem_malloc.dylib: xzm_main_malloc_zone_init_range_groups.cold.1 #1 libsystem_malloc.dylib: xzm_main_malloc_zone_init_range_groups #2 libsystem_malloc.dylib: xzm_main_malloc_zone_create #3 libsystem_malloc.dylib: __malloc_init #4 libSystem.B.dylib: libSystem_initializer #5 dyld: dyld4::Loader::findAndRunAllInitializers The binary It's a Chromium component-build test binary (browser_tests): ~1.5 GiB on disk, 5.54 GiB total VA footprint (__TEXT 517 MiB, __LINKEDIT 1.04 GiB, __PAGEZERO 4 GiB) Links 527 dylibs via @rpath All images span ~16.4 GiB of VA when loaded A simple loop that spawns this binary 200 times via posix_spawn() reliably shows 2-5 crashes. Spawning /bin/cat 1000 times produces zero failures. Investigation We did extensive analysis to understand the root cause: ASLR is irrelevant. We disabled ASLR using _POSIX_SPAWN_DISABLE_ASLR (flag 0x0100) and the failure rate is unchanged (~2% with or without). With ASLR disabled, the library addresses are identical across all crashes, confirming the VA layout itself isn't the problem. Plenty of free VA space is available. We compared the memory layout of crashing processes (from crash reports) with successful ones (via vmmap): In successful spawns, XZone places its MALLOC zones (SMALL, LARGE, metadata) in the large free regions after the loaded dylibs — for example at 0x784400000 and 0xD32000000, with 13-22 GiB contiguous free gaps available. In crashing processes, the same free regions exist (the image layout is identical), but xzm_main_malloc_zone_init_range_groups fails to reserve into them. Based on libmalloc/tests/memory_pressure.c, XZone needs 8 GiB for pointer ranges and 10 GiB for data ranges. The free gaps after the dylibs are far larger than this, yet the reservation sporadically fails. No workarounds exist. MallocNanoZone=0 has no effect (the crash is before zone configuration). The crash is entirely within system code. Questions Is this a known issue in XZone malloc on macOS 26.x? Is there any environment variable or entitlement that could work around this? Any guidance on what makes xzm_main_malloc_zone_init_range_groups fail non-deterministically when contiguous VA space is clearly available?
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2
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62
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13h
XPC communication between a sandboxed Network Extension and a privileged MachService
Hello, Is it possible for a Network Extension (running in its sandbox) to act as a client for an XPC service hosted by a Launch Daemon (e.g., to offload data processing)? Are there any specific sandbox restrictions or entitlement requirements for this type of XPC communication? Thank you in advance!
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5
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110
Activity
16h
Rosetta bug
We probably triggered a bug within Rosetta: https://github.com/docker/desktop-feedback/issues/230
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8
Activity
17h
Safari iOS 17 layout issue
Safari on iOS 17, when entering characters into text input box after deleting characters, the layout is off. Here's the HTML: <body> <div id="J001" style="display: inline-block;"> <div id="J001__0" style="display: inline-block;"> <input id="J001__0__input" style="display: inline-block; height: 28px; padding:2px; border:1px solid gray;"></div> <div id="J003__0" style="display: inline-block;"> <button id="J003__0__btn" style="display: inline-block; height:34px;">a</button> </div> </div> </body> Enter "A" into text input box. Delete "A" with the backspace(x). Enter "A" into text input box, the button position will be shifted down. iOS 17 の Safari にて、テキスト入力ボックスで文字を削除した後、文字を入力するとレイアウトが崩れます。 テキスト入力ボックスに「A」と入力します。 バックスペース(x)で「A」を削除します。 テキスト入力ボックスに「A」と入力すると、ボタンの位置が下にずれます。
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1.1k
Activity
17h
Interoperability and traffic flow when multiple Transparent Proxy providers coexist
Hello, How does macOS handle coexistence between multiple Transparent Proxy providers from different vendors if their network rules overlap and one provider modifies the traffic? Thank you in advance!
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3
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72
Activity
19h
My macOS app is unable to read a Managed Preferences plist unless the App Sandbox is disabled. Is there any solution to read the MDM plist file while the sandbox is still enabled?
I created two sample apps — one sandboxed and one non‑sandboxed. I tested reading Managed Preferences using bash commands, CFPreferencesCopyValue for a domain, and defaults read. Everything works correctly only when the sandbox is disabled in the entitlements. When the sandbox is enabled, I’m unable to read values from /Library/Managed Preferences/. Is there any supported way for a sandboxed macOS app to read an MDM-delivered preference plist under /Library/Managed Preferences/? Any guidance on the correct and Apple‑supported method would be appreciated.
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3
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186
Activity
1d
Crashes occur on iOS 26.4
Since updating the OS to 26.4, the app has been crashing more often after I launch it. The devices on which this issue has been confirmed are as follows: ・iPhone SE (2nd generation) ・9th-generation iPad ・8th-generation iPad ・5th-generation iPad mini We have confirmed that the application functions properly on all devices prior to the OS update.
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5
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627
Activity
1d
AccessorySetupKit: Can I use bluetoothNameSubstring be used without bluetoothCompanyIdentifier?
I'm integrating AccessorySetupKit for BLE earbuds discovery and running into an issue with ASDiscoveryDescriptor configuration. Our earbuds don't have a fixed Bluetooth SIG company identifier. So I'm trying to use bluetoothNameSubstring + bluetoothServiceUUID instead. However, this combination never discovers any devices. The picker appears but stays empty. As soon as I add a bluetoothCompanyIdentifier, the device is found instantly. I reproduced this with my Bose QC35 II as well, so it's not specific to our hardware. My configuration: bluetoothServiceUUID: set to our custom UUID bluetoothNameSubstring: set to a substring matching the advertised device name NSAccessorySetupBluetoothServices + NSAccessorySetupBluetoothNames both set in Info.plist supportedOptions: .bluetoothPairingLE iOS 26.3.1, iPhone 11 The documentation doesn't mention that bluetoothCompanyIdentifier is required. Is bluetoothCompanyIdentifier actually required for BLE discovery? If so, is there a recommended approach for devices that don't have a fixed company identifier?
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24
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1d
How to modify the launchctl config to start Postfix?
On Sequoia, I want to configure my postfix as a server. And for this I have to change the way postfix is started from: /System/Library/LaunchDaemons/com.apple.postfix.master.plist But this file is on the read only / file system. Then I just unloaded this startup, and made a new one in: /Library/LaunchDaemons/com.apple.postfix.master.plist and I was able to start it. But on the next system boot, the system one in /System/Library/LaunchDaemons was started again. How should I cleanly and permanently achieve this server basic modification?
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148
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1d
26.4 beta and RC versions are unable to be created on anything but 26.4 beta host OS
We're trying to create 26.4 beta and RC VMs on 15.x and 26.3 host OS' without success. We see Tue Mar 17 17:27:36 40 anka.log (install) 45803: failed to install macOS: Error Domain=VZErrorDomain Code=10006 "Installation requires a software update." UserInfo={NSLocalizedFailure=A software update is required to complete the installation., NSLocalizedFailureReason=Installation requires a software update.} Yet, if we create it the same way on 26.4 beta host OS, it works. We've tried the usual tricks of installing latest Xcode and preparing it (accepting license, etc). But, they don't work on 26.3 and 15.x. What's the trick to get the creation of 26.4 to work on <= 26.3 host OS?
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17
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601
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3d
Custom icons for folder aliases not showing
Problem: custom icons for folder aliases not showing System drive and external drive custom alias folder icons don't showup on desktop or external drive (OS14.6 Sonoma 2023); they only show-up as plain folders or with an odd document icon. Alias doesn't connect to image; however it's there, easily accessible via spacebar. Finder doesn't save the custom icon to the alias. See below for workaround. Summary: I have custom alias icons on my desktop linking to their source files on the system drive and external drive.. however they do not display the custom icon. After upgrading from OS10.14 Mojave to OS14.6 Sonoma 2023, system drive & external drive custom alias icons no longer display the icon on either drive (there is a work-around for Mojave; see history section). Personal impact: hampered file navigation and workflow; I'm lost, can't tell where anything is; not having my icons makes it especially difficult to navigate my files and hampers my workflow significantly. Desired outcome: all custom icons for folder aliases linking to source files (on system & external drives) appear on the desktop, and in all directories on system & external drives (including encrypted external drives). Status.. August 2024: called apple support, they said there is no solution, and there are no plans to fix it, and no plans for a fix in OS 15 Sequoia (in public beta now) Action: ❯ leave feedback at https://www.apple.com/feedback/macos/ ❯ join this campaign to fix this once and for all! -- After 20 years of dealing with this issue.. we need to fix this. History: ▪ OS 10.14 Mojave 2018: external drive alias icons don't work; because upon startup, the icon images for these files disappear; because when system starts it loads the system drive icons but not the external drive icons because it's password protected, hence icon information does not get loaded; alias icons can't connect with unmounted external drive @ boot; however it's there, easily accessible via spacebar the FIX: alias the icons on the desktop each time after boot, however the names are altered ▪ OS X 10.11 El Cap 2015: drag the icons to a folder then back to desktop.. sometimes this works I stayed on OS9 as long as possible because of the OS10 icon problem ▪ OS 9: all custom alias folder icons worked fine Givens: space bar has fast access to icon -highlight alias and press space bar -- seems that it would be a simple solution, since the image is there -- get info for alias also has the image in preview How to make a custom icon: open a pic (typically from a screenshot; .png), select image with cursor with shift key down (for a perfect square), copy ⌘C, click target folder, get info ⌘I, click on folder icon on top left corner, paste ⌘V Fix -- How? --make a solution approach for a macOS dev? some bash process to link to icon; how to access icon Swift? process to renew the alias icon process goes through all desktop icons.. fixes them; new icon, correct name routine where all icons on desktop link to their files easily making a new alias.. as easy as making a regular alias; cammand L, etc make alias search for the image app that makes alias create custom desktop.. a GUI w links -- INTERIM FIX / WORKAROUND create a new folder on your desktop, name it, place it's alias inside the folder, fix the icon, when you open the desktop folder, you will then have to click on the alias --this is very time-consuming and tedious note: there may be easier options for OSs prior to Sonoma; review History section workflow: symbol note: ⇧ shift, ⌃ control, ⌥ option, ⌘ cammand create new folder on desktop ⌘⇧N , name it.. if the name is already taken by the alias, change the alias's name; for example.. alias it ⌘^A click on this new folder then ⌘I (get info) click on the alias, open source location ⌘R (or ⌘⌥^A on older OSs), click on source file (if not highlighted) then ⌘I (get info) , click on folder icon on top left corner, copy ⌘C click on the get-info window you opened for the new folder, click on folder icon on top left corner, paste ⌘V (if not working see ¹ below), close each of these windows with ⌘W place the associated aliased folder into the new folder you can also do this in groups of folders (3-6 seems is optimal).. for example.. move 3 alias icons to clear area on desktop, create 3 new folders and place them below the aliases, select all aliases and ⌘C, open a text document and ⌘V, fix names & name new folders, select new folders, ⌘I, select target aliases, ⌘R, ⌘I for each, move the alias windows below the new folder windows, copy/paste icons from source to new file, close these windows, place alias folders into new folders ¹ if paste function not working.. move on to the next folder and come back.. it can be moody, if it's not working at all.. restart the computer note2: some icons now have a yellow streak at the bottom let us know if you have any solutions or workarounds, or can code this (provide a script or app)
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2.2k
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4d
Cellular not initializing on iPadOS 26.4 (resolved by network reset)
We are seeing an issue after updating iPads to iPadOS 26.4 where cellular service is lost until network settings are reset. Environment: Devices managed via Apple Business Manager and Microsoft Intune Carrier: Verizon Confirmed affected devices: iPad (9th generation) eSIM Behavior: After update, device shows no cellular service No prompt to re-activate or re-add the cellular plan The plan appears to still be present on the device Workaround observed: Resetting Network Settings restores service Notes: This does not appear to be a provisioning issue (no need to re-add eSIM) Behavior suggests the cellular/eSIM state may not be initializing correctly after update Toggling Cellular or Airplane mode has not yet been tested for service restoration. We have not yet confirmed whether devices using a physical SIM are affected Still gathering data on scope across additional iPad models Additional observation: We have not observed this behavior on iPhones (e.g., iPhone 16 on iOS 26.4 with LTE remains unaffected) Has anyone else observed similar behavior on iPadOS 26.4, particularly on managed devices or eSIM configurations?
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118
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4d
The M5 Pro does not connect to the Wi-Fi AP using RADIUS when NetworkExtension Activiate.
The M5 Pro does not connect to the Wi-Fi AP using RADIUS when NetworkExtension Activiate. The M1 and M2 Pro worked, but only the M5 Pro MacBook Pro did not work. If you deactivate NetworkExtension, it connects to the AP, and afterwards, it works even if you activate NetworkExtension.
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65
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4d
copyfile Sometimes Fails to copy .DS_Store when Copying a Folder But Does Not Report Usable Error
Testing copyfile on a folder on an external volume (which takes a bit a of time) I'm running into an issue where copyfile gets to the end of the operation and then just fails. In the callback I can see that the failure occurs on a .DS_Store file inside the folder. So for a .DS_Store it is simple enough for me to just ignore the error and return COPYFILE_SKIP but the somewhat more concerning issue here is that the true error reason is seemingly not reported? In the callback if I read errno it is 0. When copyfile returns it returns -1 after I return COPYFILE_QUIT (and errno is 0) so I don't know what the error is or the appropriate way to handle it. For .DS_Store just skipping seems reasonable but when copying a folder it may be appropriate to get the true failure reason. But checking the last path component of source path seems like a hack way to handle errors. If a file in the copying folder with important user data I can't just silently skip it - it isn't clear to me how I should properly proceed in a situation where I can't get the actual reason for the failure.
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5d