Issue Summary

After auto-conversion Phase 2 (legacy editor deprecation), file attachments on Confluence Cloud pages fail to preview and display the error message "We couldn't load the file." File extensions appear to be missing or corrupted on affected attachments. Users can only open the documents after downloading them and manually adding the correct file extension by trial and error.

Steps to Reproduce

 1.  Navigate to a Confluence Cloud page with file attachments that has been through auto-conversion Phase 2.
 2.  Attempt to view the inline file preview of any attached document.
 3.  Observe the error message displayed.

Expected Results

The file preview loads successfully and the attachment is viewable inline on the Confluence page.

Actual Results

The file preview fails to load and displays the error message: "We couldn't load the file."
File extensions appear to be missing or corrupted on the attachments after auto-conversion Phase 2. Users can only open the documents after manually appending the correct file extension upon download.

Workaround

Download the affected attachment and manually add the correct file extension (e.g. .pdf, .docx, .msg) before opening. Alternatively, detach and re-upload the file with the correct extension to restore preview functionality on the page.