J4.x:Media Manager opens with error
From Joomla! Documentation
Errors reported
Error Property 'mime_type' of argument 'item' of event onFetchMediaItems has a wrong item. Valid: string
Versions affected
General Information
This pertains only to Joomla! version(s): 4.3.0, 4.3.1
What is the cause
This is caused by your server missing the php module fileinfo
How to fix
Request that your hosting provider enables the fileinfo module in php