Xcode 26.1 RC issue

Developer Tools & Services Xcode
jhowlin OP
Created 1w
Replies 20
Boosts 22
Views 1.8k
Participants 14

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  20
Boosts  22
Views  1.8k
Participants  14
RickMaddy OP
1w

I've been seeing the same issue for a while now. I have both Xcode 26.0 and Xcode 26.1 beta 3. Running either causes the same issue as soon as I open an iOS/iPadOS 26.1 simulator.

I only have a missing wallpaper on iPad simulators with iPadOS 26.1. iPhone simulators show the wallpaper. But either causes the CPU spike due to the ReportCrash process.

I can have all of the iOS/iPadOS 26.0 simulators running that I want with no CPU spike. Launch a single iOS/iPadOS 26.1 simulator and in seconds my CPU spikes and stays there. Close that one simulator and everything goes back to normal.

I filed FB20868503

4
jhowlin OP
1w

Good to know it's not just me!

0
RickMaddy OP
1w

@jhowlin Make sure you file a bug report using Feedback Assistant. Apple needs to know that more than one person is having this issue.

0
soapbox OP
1w

I am seeing this too.

0
RickMaddy OP
1w

@soapbox Make sure you file a bug report using Feedback Assistant.

0
jhowlin OP
4d

Still an issue in 26.1 official release

6
zdzichukowalski OP
4d

Same for me. Happens for SwiftUI preview in xcode and also when running the simulator. It drains like 1% battery per minute or faster.

2
MattBFX OP
4d

Seeing the exact same issue here. Wondered why I was constantly hitting high CPU usage, crash reporter constantly spitting our reports for MercuryPosterExtension.

0
okorolevych OP
3d

Was investigating my issue https://developer.apple.com/forums/thread/805993#805993021 and this led me to issue with CoreSimulator process itself. The process is not killed and is actually leaking. This is why I see high CPU usage as well. Do you think that these issues may be related?

0
RickMaddy OP
3d

Are all of you posting bug reports with Feedback Assistant? Make sure you do. Be sure your report includes the steps needed to reproduce the issue and include the sysdiagnose attachment.

What version of macOS is everyone seeing this issue with? In my case I'm running macOS 26.0.1. I don't know if the version of macOS matters or not. I see the issue with both Xcode 26 and Xcode 26.1. It's just requires starting an iOS/iPadOS 26.1 simulator. I have no issue when running an iOS/iPadOS 26.0 simulator.

0
AnnArborMark OP
3d

This still happens with Xcode 26.2 that just came out today. I have reported feedback, and also linked to this discussion in my feedback report.

4
mallow OP
3d

Same problem here with ReportCrash. But I see it even with the iOS 26.0 Simulator. It started in Xcode 26.1. I didn't have this issue in Xcode 26.0.

Reported yesterday via Feedback Assistant: FB20918609

I can't work like this. My MacBook is getting extremely hot in seconds.

0
gabor.sajo OP
2d

Xcode 26.2 beta 1 and iOS simulator 26.2 beta 1 has the same issue :(((((

0
gabor.sajo OP
2d

I think I may have found a workaround. Installing & using the iOS 26.0.1 simulator under Xcode 26.1 does not seem to engage the ReportCrash process. So far so good!

1
Martin81 OP
2d

You can also fix this by setting a wallpaper in the Simulator. The iOS 26.1 simulators are missing the default wallpapers, which can trigger a crash or loop in the MercuryPosterExtension. This has happened several times in the past with other Xcode releases.

I’m not sure how to set a wallpaper in the #Preview Simulator, but with this workaround you can at least debug and run apps in the regular Simulator without the high CPU load.

5
Xcode 26.1 RC issue
First post date Last post date
 
 
Q