Does your Canvas in Xcode crash all the time due to AXRemoteElement-BackgroundFetch?

Question

Created 3w

Replies 6

Boosts 4

Participants 8

Hi everyone, yesterday I updated my macOS and Xcode to the latest versions and today I have the strangest thing: Canvas is always crashing whenever I click it, in any and all my Projects. The full Simulator works just fine; only the Preview Canvas crashes.

All the crash reports say it's because of AXRemoteElement-BackgroundFetch, and ChatGPT says it's not because of my code. These are very simple Projects, just for experimentation. Nothing complex, just native code while I follow examples in a SwiftUI book.

Anyone else having this issue?

Translated Report (Full Report Below)
-------------------------------------
Process:             PreviewShell [2179]
Path:                /Volumes/VOLUME/*/PreviewShell.app/PreviewShell
Identifier:          com.apple.PreviewShell
Version:             16.0 (23.40.29)
Code Type:           ARM-64 (Native)
Role:                Foreground
Parent Process:      launchd_sim [1405]
Coalition:           com.apple.CoreSimulator.SimDevice.E9525D59-3C07-43F9-ACC9-18CF5DD0DAA1 [1516]
Responsible Process: SimulatorTrampoline [1120]
User ID:             501

Date/Time:           2026-03-26 15:00:02.6060 +0200
Launch Time:         2026-03-26 14:57:33.8870 +0200
Hardware Model:      Mac17,9
OS Version:          macOS 26.4 (25E246)
Release Type:        User

Crash Reporter Key:  1DC4EA68-804A-D651-804B-C2E0C13D9B87
Incident Identifier: F3F1A52F-AFF9-4470-A216-7364FCB5B7E6

Time Awake Since Boot: 1100 seconds

System Integrity Protection: enabled

Triggered by Thread: 4, Dispatch Queue: AXRemoteElement-BackgroundFetch

Exception Type:    EXC_BAD_ACCESS (SIGBUS)
Exception Subtype: KERN_PROTECTION_FAILURE at 0x000000016b6bfff0
Exception Message: Could not determine thread index for stack guard region
Exception Codes:   0x0000000000000002, 0x000000016b6bfff0

Termination Reason:  Namespace SIGNAL, Code 10, Bus error: 10
Terminating Process: exc handler [2179]

Boost

Answer 1

humblehacker OP

3w

Same. I thought it might be an Xcode 26.4 issue. But the same thing happens on Xcode 26.3. I'm on macOS Tahoe 26.4 (25E246).

0

Answer 2

alecnash OP

3w

Hey, I had the same issue. It’s caused by the 26.4 simulator you’re using in the canvas. Go to “Manage Run Destinations,” create a new one with 26.2, and set that to run in the canvas.

Hope Apple fixes it at some point.

2

Answer 3

Efthymis OP

3w

Accepted Answer

I guess our only two options till the next version are: a) revert to an iOS 26.2 simulator b) just preview everything in the actual Simulator and never click on the Canvas no matter what

0

Answer 4

SkiDev81 OP

2w

I am having the same issue on both of my machines (both running Xcode 26.4 and 26.4 simulators.)

After setting the simulator back to iOS 26.2, I can work in the SwiftUI canvas.

0

Answer 5

Morphheus OP

2w

Same issue here. After analyzing the crash log in detail, I can confirm this is not related to our code or derived data cache.

Root cause: Infinite recursion (10,915 levels deep) in -[AXElement customActions] inside AXRuntime.framework, triggered by UIAccessibilityHierarchyEncoder when PreviewShell tries to serialize the accessibility tree on the AXRemoteElement-BackgroundFetch dispatch queue. The thread stack overflows into the stack guard region, causing EXC_BAD_ACCESS (SIGBUS) / KERN_PROTECTION_FAILURE.

Environment:

macOS 26.5 beta (25F5042g)
Xcode 26.4 (17E192)

Confirmed workaround: Setting a physical iOS device as the preview destination works correctly. The bug is isolated to the simulator runtime — PreviewShell on device does not go through the affected AXRemoteElement path.

I've already filed a feedback report with the full crash log attached. I'd encourage everyone affected to file their own report — the more Incident IDs Apple has, the faster this gets prioritized.

5

Answer 6

teejK OP

18h

How are they not testing this basic feature before they push an update like this????

0