Summary

Some PDFs are not displaying in macros in Confluence pages when view if their media type is application/pdf. Those affected PDFs are failing in all Confluence pages, even if you add it to a different clean Confluence instance running the same version

Steps to Reproduce

1. Edit any Confluence page
2. Add the PDF to the page and save it (displaying the PDF as a macro)
3. Make sure that the media type is application/pdf
4. Click the PDF macro in the page to view it

Expected Results

The PDF is displayed.

Actual Results

The following error is shown:

Ouch! We can't load the PDF.

JS console shows us this:

Unrecognized Content-Security-Policy directive 'frame-ancestors'.
Failed to load resource: cancelled

Notes

This can be seen consistently in Safari and in Firefox. Chrome is not affected (not tested in IE/Edge).

Workarounds

Workaround 1

Changing the media type to anything other than application/pdf resolves this issue:

1. Go to the page where the attachment is
2. Click '...' >> 'Attachments (7)'
3. Find the affected PDF and click 'Properties' next to it
4. Edit New Content Type to something else, we advise adding a single character, so it's easy to undo if needed
5. Save it

Workaround 2

Ask Atlassian Support to disable the filestore.direct.download dark feature. This will require a downtime.