Just updated the latest advanced module manager (10.0.22) and Sourcerer (10.1.2) on J4.4.5, and getting this error when I try to upload an image to the media manager. It dose upload the image (can see it when using FTP) but can't see the images in the joomla media component.
I have this exact same problem which I only noticed yesterday - same extensions (Sourcerer and Advanced Module Manager) but on Joomla 5.1.1 as well as a site with Joomla 4. When I disable the System - Regular Labs Library it stops.
Hi Bart.
Did you try to reinstall the module? I ask this because installing the library alone (as described in my post), even if the version appears to be the same, it solves the problem.