Recently we have been upgrading and migrating lots of Joomla 3 websites over to Joomla 4 and from time to time, the Joomla Update screen does not show the Joomla 4 upgrade information. In most cases, this is because the Joomla 3 Update Channel is set to the Default Channel. To check and change this, while you are on the Joomla Update screen, press the Options button in the top right hand corner and see what Update Channel you are on. To see Joomla 4, this needs to be set to the Joomla Next Update Channel.
However, in some instances we have found that even with that setting correct - the Joomla 4 update does now show.
This probem occurs when the Joomla! Core update site is disabled in the database. When an update site can't be reached for whatever reason, the system will automatically disable it in Extensions > Manage > Update Sites so that it is not constantly checking an update site that may have gone offline. However, there is no mechanism to automatically re-enable a disabled update site, so to re-enable this setting manually navigate into Extensions > Manage > Update Sites. In our example, it is the Joomla Core update site that is disabled and preventing the website from seeing the available Joomla update so we re-enable the record called Joomla! Core.
Once that is complete, you can now navigate back to the Joomla Update screen and your Joomla 4 update should be available. Before you update to Joomla 4, make sure you have a viable backup. Also make sure to check through each of the items in the Joomla 4 update pre-check and solve any issues there before proceeding. We advise that Joomla 4 upgrades should always be done on a testing server and not directly on the live site. Get in touch with our team to get a free assessment of your Joomla 4 upgrade status.