Issue Summary

When a page has an unknown/unsupported element in its storage format, the content might not be displayed as expected. Instead of it, there's an error message: 

We've hit a snag
The issue should resolve on its own, but if it keeps happening, ask your admin to contact our support team and give them:

• The URL of this page
• The code associated with this error: #####

Example of unknown/unsupported elements found so far

<p /></p>

<<br />

;f ree

 ;closed

<time class="non-editable">_=:</time>

<p class="media-group"><ac:link><ri:attachment

Steps to Reproduce

• These elements could have been added when creating or updating a page through the REST API.
• Most cases happen with Legacy editor.

Expected Results

The content properly should be displayed properly.

Actual Results

Instead of the content, we can see the following error message:

We’ve hit a snag

The issue should resolve on its own, but if it keeps happening, ask your admin to contact our support team and give them:

• The URL of this page
• The code associated with this error: #####

 Refresh page

Even the editing mode seems to be affected and might not open, depending on the case:

Logs we gathered so far:

react-dom.production.min.js:209 Error: Failed to parse ADF: <div class="error fatal-render-error">Error: RuntimeException occurred while performing an XHTML storage transformation (Expected p end element but got: <p>)</div>

Failed to parse ADF: <div class="error fatal-render-error">Error: RuntimeException occurred while performing an XHTML storage transformation (Expected one of [thead, tbody, tfoot, tr] start elements but got: <p>)</div>

 
Failed to parse ADF: <div class="error fatal-render-error">Error: RuntimeException occurred while performing an XHTML storage transformation (Text '_=:' could not be parsed at index 0)</div>

Workaround

We have some alternatives for scenarios like this:

• You can restore a previous version of the affected page and it should work properly. As a heads up: it is important to say that restoring a previous version might result in data loss IF you have added any content on the last published version.
• If you prefer, the support team can try to apply an update on the affected page. If you choose this option, kindly share the code associated with the error you've received, mention this bug and we will work on trying to find which element could be causing this. 
  This option is strongly suggested if you would like to prevent data loss as much as possible.
• Another suggestion would be to prioritize creating pages using the new editor whenever possible. Additionally, for existing pages that are still utilizing the Legacy editor, consider converting them to the new editor whenever feasible. Taking these steps proactively could significantly reduce the likelihood of encountering similar issues in the future.