[Bug] App crashes on login (QtWebEngineCore SIGTRAP) on macOS 26.3 with M5 Max

[mannewolff]

⚠️ Before submitting, please verify the following: ⚠️

• This is a bug, not a question or a configuration issue.
• This issue is not already reported on Github (I have searched for it).
• Nextcloud Server and Desktop Client are up to date. See Server Maintenance and Release Schedule and Desktop Releases for supported versions.
• I agree to follow Nextcloud's Code of Conduct

Bug description

Bug description

The desktop client crashes immediately when the login wizard tries to load the server URL in the embedded WebView. The app never completes the login flow.
Steps to reproduce

Install Nextcloud Desktop 33.0.5 on macOS 26.3 (Tahoe) on Apple Silicon (M5 Max)
Open the app and start the login wizard
Enter the server URL and click "Next" / "Log in"
App crashes immediately

Expected behavior
The login WebView opens and the OAuth/Flow v2 login completes successfully.
Actual behavior
The app crashes with EXC_BREAKPOINT (SIGTRAP) in ThreadPoolSingleThreadForegroundBlocking0 inside QtWebEngineCore. The crash is triggered by OCC::WebViewPage::initializePage() → OCC::WebView::setUrl() → QWebEnginePage::setUrl() → QtWebEngineCore::WebContentsAdapter::load().
This appears to be a CHECK assertion failure inside the embedded Chromium (QtWebEngineCore), not a null pointer or memory corruption.
Client machine

Hardware: MacBook Pro with Apple M5 Max (Mac17,7)
OS: macOS 26.3 (25D2125)
Nextcloud Desktop: 33.0.5 (ARM-64, native, not translated)
Qt: 6.10.2
QtWebEngineCore: 6.10.2

Crash details

Exception Type: EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x0000000000000001, 0x000000012a34fadc
Termination Reason: Namespace SIGNAL, Code 5, Trace/BPT trap: 5
Faulting Thread: ThreadPoolSingleThreadForegroundBlocking0

Crashing stack (Thread 41):
0 QtWebEngineCore 0x12a34fadc (offset 167033564)
1 QtWebEngineCore 0x124d321f0 (offset 76734960)
2 QtWebEngineCore 0x124d31cc8 (offset 76733640)
...

Trigger stack (Thread 0 / CrBrowserMain):
OCC::WebViewPage::initializePage()
OCC::WebView::setUrl(QUrl const&)
QWebEnginePage::setUrl(QUrl const&)
QtWebEngineCore::WebContentsAdapter::load(QUrl const&)

Full crash report attached.
Additional context

This is a clean install (second attempt after removing all Nextcloud data from ~/Library/Group Containers/com.nextcloud.desktopclient)
The crash happens 100% reproducibly on the first interaction with the login WebView
No external modifications to the process (task_for_pid: 0)
System Integrity Protection: enabled

Steps to reproduce

1. Right click on the file
2. Click on Share Options
3. The share dialog does not display the option to share by e-mail
   ...

Expected behavior

When clicking on the share dialog, share by e-mail should be an option.
...

Which files are affected by this bug

I dont know

Operating system

macOS

Which version of the operating system you are running.

macOS 26.3 (25D2125)

Installation method

Official Linux AppImage

Nextcloud Server version

33.0.4

Nextcloud Desktop Client version

33.0.4

Did this occur after an update or on a clean installation?

Minor version update (i.e. 33.0.0 → 33.0.1)

Are you using the Nextcloud Server Encryption module?

Yes

Are you using an external user-backend?

• Default internal user-backend
• LDAP or Active Directory
• SSO - SAML
• Other

Nextcloud Server logs

Additional info

No response