Your comments

Useful to note that FileRun never overwrites a file without saving the exiting version.

You can only prevent yourself from uploading new files with the same filename by disabling the file versioning system from the FileRun control, by setting the number of kept old versions to 0. You won't be given options for overwriting, you just won't be able to.

File uploads in FileRun will never do automatic renames. It's not something users expect.

The first one is the date of the file creation (taken from the server's filesystem). The second is the date the photo was taken (taken from the metadata inside the file).

I can provide a solution, but requires good PHP coding knowledge. Let me know if you are interested. Again, note that it would require you to write PHP code.

I know it might sound strange, but are you able to create a new folder, using FileRun, inside the same folder as the file that fails to preview? If not, it might be that PHP doesn't have write permissions to the folder, thus failing to save a generated resized version of the image file.

I assume you have enabled ImageMagick from FileRun's control panel, and configured its path. When you click to test the configured path, what is the result?

Temporarily setting "display_errors" to "On", in your PHP config, and trying the update again, the FileRun update log will include some more information which should be helpful in identifying what exactly is it that goes wrong.

That is indeed a pretty close explanation. Some MySQL servers don't allow a client (in this case PHP/FileRun) to be connected without doing anything (without running any queries) for too long (yes, even if it's just for a few seconds).

So when logging in, FileRun connects to the MySQL server, and performs the authentication, then because of the notifications settings, it is trying to send out some e-mails, trying to communicate with an inaccessible e-mail server (due to DNS issues), dragging things for too long before trying to communicate again with the MySQL server, which in the meantime it already dropped the client's connection, resulting in the error which prevents the login flow.

The download is no longer available as the theme will be included, in a backwards-incompatible way, in the upcoming FileRun update.

We'll add the thumbs back in the list mode, with the next update.