Safari infinite loading when opening tagged Office documents

Environment

• Nextcloud 33.0.5
• richdocuments 10.1.3
• Safari on macOS Tahoe 26.5.1
• MacBook Pro M2 Max
• Firefox works correctly
• Reproduced on three independent installations:
  • Manual Nextcloud installation on Ubuntu LXC (Proxmox)
  • Nextcloud AIO installation #1
  • Nextcloud AIO installation #2

Steps to reproduce

1. Create or upload a DOCX or XLSX file.
2. Open the file in Safari via Nextcloud Office.
3. The document opens normally.
4. Add a file tag (keyword/tag) to the file.
5. Close the document.
6. Reopen the same document in Safari.

Expected result

The document opens normally.

Actual result

Safari shows an endless loading screen and the document never opens.

Additional observations

• Removing the tag immediately makes the document open again in Safari.
• Firefox opens the same tagged document without any issue.
• PDF files and JPG files with tags work correctly.
• The issue only affects Office documents (DOCX and XLSX tested).
• The issue started after upgrading from Nextcloud 32.x to Nextcloud 33.x.
• The same behavior occurs on three independent Nextcloud installations.
• The problem is fully reproducible.

Safari Console Error

InvalidCharacterError: Invalid qualified name: '@canAssign'

Additional console messages related to the loading process were observed, but this JavaScript error appears consistently when the issue occurs.

Summary

Office documents (DOCX/XLSX) that have one or more file tags assigned cannot be opened in Safari and remain stuck on an endless loading screen.

The same files open correctly:

• in Firefox
• after removing the file tag(s)

This suggests a Safari-specific frontend issue related to tagged Office documents in Nextcloud 33 / richdocuments 10.1.3.

No source file or test is named. Reproduce the tagged DOCX/XLSX reopening steps in Safari and inspect the Safari console for the recurring InvalidCharacterError: Invalid qualified name: '@canAssign'; compare with Firefox and untagged files. Done means tagged Office documents open normally in Safari without endless loading.