Upload file button broken

[Erel]

There seems to be an issue with uploading files with the Upload a File button.

The following error appears:

As a workaround you can drag and drop files into the post. This works fine.

I'm further investigating this issue.

 

[Erel]

This issue is now resolved!

Thank you @LucaMs for reporting another issue which eventually lead me to the solution (with the help of Xenforo support).