Xcode 26.1 RC issue

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.

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.

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.

Still reproducible in Xcode 26.2 beta (17C5013i).

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

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

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

Xcode 26.1 RC issue
 
 
Q