Recently have been experiencing an issue where I cannot publish any new pages on Confluence Cloud where ac:link macros try to utilize the ri:page tag. Using an explicit example found in Confluence’s storage format documentation, when trying to publish a new page with the contents:
<ac:link>
<ri:page ri:content-title="Page Title" />
<ac:plain-text-link-body>
<![CDATA[Link to another Confluence Page]]>
</ac:plain-text-link-body>
</ac:link>
Confluence will report a 400 error with the message:
Content contains unsupported extensions and cannot be edited in Fabric editor
If the content drops the ri:page tag:
<ri:page ri:content-title="Page Title" />
The publish attempt succeeds (with a undesired/broken link).
It appears this only applies to new page events. Updating an existing page with the same contents yields a successful publish event. Not sure when this started.