An extension isn't ready for the new version
Update it, ask its developer, or replace it. If you don't use it, uninstall it before you upgrade.
Why it matters
An extension that uses code removed in the new Joomla version can stop your site's front end or administrator from loading. This is the most common cause of errors after a major upgrade.
Your options
- Update it. Check the developer's site or the Joomla Extensions Directory for a version made for the new Joomla.
- Ask the developer whether and when an update is coming.
- Test it with the compatibility plugin. Many Joomla 5 extensions work on Joomla 6 with Behaviour - Backward Compatibility 6 on. Try it on a test copy.
- Replace it with a maintained extension that does the same job.
- Remove it if you don't really use it: fewer extensions means fewer updates and fewer risks.
Good to know
- Disable or uninstall the extension before you upgrade, not after: a broken extension can lock you out of the administrator.
- Check the Vulnerable Extensions List too: an abandoned extension may also be a security risk.
Sources
- Joomla 5 to 6 Planning and Upgrade Step by Step – Joomla User Guide
- Vulnerable Extensions – Joomla User Guide
- The Joomla Extensions Directory – Joomla User Guide
