[Bug]: DOCX to PDF export broken in richdocuments 10.2.0 but works in 10.1.3

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Describe the bug

After upgrading Nextcloud Office (richdocuments) from version 10.1.3 to 10.2.0, exporting DOCX documents to PDF stops working.

The same setup works correctly with richdocuments 10.1.3.

The issue is reproducible every time:

• richdocuments 10.1.3 → DOCX to PDF export works
• richdocuments 10.2.0 → DOCX to PDF export fails

No changes were made to the Collabora container, Nextcloud configuration, MariaDB, Redis, reverse proxy, or server environment between tests.

To Reproduce

1. Install Nextcloud Office (richdocuments) 10.1.3.
2. Open any DOCX document in Nextcloud Office.
3. Export or download the document as PDF.
4. PDF export works correctly.
5. Upgrade Nextcloud Office to richdocuments 10.2.0.
6. Open the same DOCX document.
7. Export or download the document as PDF.
8. PDF export fails.

Expected behavior

DOCX documents should be converted and downloaded as PDF exactly as in richdocuments 10.1.3.

Actual behavior

PDF export stops working after upgrading to richdocuments 10.2.0.

Environment

• Nextcloud Hub 26 Winter
• Nextcloud 33.0.5.1
• Nextcloud Office (richdocuments) 10.2.0
• Collabora Online (unchanged between tests)
• MariaDB 10.11
• Redis enabled
• Docker / Container Station
• QNAP TS-264

Additional information

The problem was verified by rolling back from richdocuments 10.2.0 to richdocuments 10.1.3.

After rollback, PDF export immediately started working again without any changes to Collabora or the server configuration.

This strongly suggests a regression introduced in richdocuments 10.2.0.

[BernieO]

Possibly related to #5755