Xcode 26.1 RC issue

Developer Tools & Services Xcode
jhowlin OP
Created 2w
Replies 30
Boosts 30
Views 3.1k
Participants 26

I'm seeing a lot of unexpected CPU usage when running the iOS 26.1 simulator. Looks like a "MercuryPosterExtension" is crashing over and over, which then causes the "ReportCrash" process to run, presumably to create the crash report.

Doesn't happen on device, nor on iOS 26.0 simulator. I suspect MercuryPoster is related to wallpaper. I also don't see any wallpaper background in my simulator.

Few lines from the stack trace:

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread 0 libxpc.dylib 0x18011defc _xpc_api_misuse + 88

1 libxpc.dylib 0x18012e16c _xpc_shmem_create_with_prot.cold.1 + 24

2 libxpc.dylib 0x180113a70 _xpc_shmem_create_with_prot + 276

3 MTLSimDriver 0x23795ed48 -[MTLSimDevice newBufferWithLength:options:pointer:copyBytes:deallocator:] + 260

4 MercuryPosterExtension 0x10081d21c 0x100758000 + 807452

13 PosterKit 0x240d003d8 -[PRRenderer scene:willConnectToSession:options:] + 648

14 UIKitCore 0x1856bcf18 +[UIScene _sceneForFBSScene:create:withSession:connectionOptions:] + 956

Answered by RickMaddy in 864990022

@Martin81 I get the ReportCrash issue running an iOS 26.1 simulator such as an iPhone 17 Pro. And it is showing a wallpaper. The only sims that don't show a wallpaper in my case are iPad simulators running iPadOS 26.1.

But here's what's really weird. I ran the Photos app in the iPhone 17 Pro simulator (which is showing the default wallpaper and causing high CPU). While viewing one of the stock simulator photos I chose "Use as Wallpaper". I went through the steps. Even though the chosen image is now appearing as a black wallpaper, it did fix the high CPU problem for that simulator.

Such a strange set of bugs.

Replies  30
Boosts  30
Views  3.1k
Participants  26
weak OP
6d

I've just disabled ReportCrash:

launchctl unload -w /System/Library/LaunchAgents/com.apple.ReportCrash.plist 
sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.ReportCrash.Root.plist

To re-enable:

launchctl load -w /System/Library/LaunchAgents/com.apple.ReportCrash.plist 
sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.ReportCrash.Root.plist

Overall it's a sad state of affairs tbh.

4
RickMaddy OP
6d
Accepted Answer

@Martin81 I get the ReportCrash issue running an iOS 26.1 simulator such as an iPhone 17 Pro. And it is showing a wallpaper. The only sims that don't show a wallpaper in my case are iPad simulators running iPadOS 26.1.

But here's what's really weird. I ran the Photos app in the iPhone 17 Pro simulator (which is showing the default wallpaper and causing high CPU). While viewing one of the stock simulator photos I chose "Use as Wallpaper". I went through the steps. Even though the chosen image is now appearing as a black wallpaper, it did fix the high CPU problem for that simulator.

Such a strange set of bugs.

3
ramicake OP
6d

Still reproducible in Xcode 26.2 beta (17C5013i).

[Update]: Issue was resolved when I upgraded to macOS 26.1 (25B78).

0
gshaw OP
5d

Confirmed settings wallpaper in simulator resolved the high CPU via ReportCrash.

1
ibatis OP
4d

The problem is also in SwiftUI preview simulator. How to change the wallpaper there ??

4
RanduSoft OP
2d

the issue is NOT fixed in macOS 26.1, nor is it possible as it's an issue in the simulator itself.

disabling the reportcrash service is the only proper fix that also solves the preview simulator:

launchctl unload -w /System/Library/LaunchAgents/com.apple.ReportCrash.plist

sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.ReportCrash.Root.plist
4
InerziaSoft OP
2d

Using SwiftUI, the crashes of MercuryPosterExtension (half a second of distance from one another) are showing directly and make it impossible to use Xcode. Filed a feedback (FB20978029). Just to note: the Feedback app crashed during the process...

0
imranshk OP
2d

simctl Diagnose To capture an simctl diagnose, please follow the instructions below to gather logging. Instructions

  1. Launch Terminal.app (/Applications/Utilities/Terminal.app).

  2. Enter the command below at the command prompt, followed by the Return key: $ xcrun simctl diagnose

  3. Type in your sudo password and press the enter key.

  4. Press the enter key again when prompted to start the sysdiagnose process.

  5. Attach the resulting output file that’s generated in /private/var/tmp to your report.

0
HeGe2 OP
2d

Same here. Changing the wallpaper did not help.

0
Xaxxus OP
1d

Seems this is still happening in the 26.2 beta as well.

2
mkdev OP
18h

Is this still happening in 26.1.1? The release notes don't mention this issue.

2
shreddit OP
14h

Looking good so far, ReportCrash is no longer tanking the cpu while a preview is open.

1
volmag OP
13h

I can confirm that 26.1.1 fixes it

1
DDP OP
10h

Updating the iOS 26.1 simulator from 23B80 to 23B86 looks good. The simulator shows wallpaper. So far ReportCrash doesn't have high CPU usage with simulator or canvas previews.

1
jhowlin OP
9h

Yep. 26.1.1 fixes the issue. Thanks Xcode folks and everyone else here.

0
Xcode 26.1 RC issue
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