If after migrating from Joomla 3 to Joomla 4 your articles show in the front end of the site and are listed in the content table of your database BUT some or all of your articles are not showing in the article manager in the admin area of your site, this might be the fix you are looking for.
If this fix does not work for you, try the video at (No Articles Appearing in the Article Manager after Migrating to Joomla 4) which solves a very similar problem in your J4 database.
If you are getting an "Error: 0 Class "ZipArchive" not found" 500 Server Error in Joomla this may very well be the fix you are looking for.1
If your post Joomla 4 migration site has an extra blue menu toggle box at the top of every page in backend, this might be the fix you are looking for.
If there are no articles showing in the Articles Manager after you migrate from Joomla 3 to 4, this might be the fix.
