Problems when uploading a file

[JP Schriefer]

I'm trying to upload a file on LEX but every time errors appear. First came the message that an image was not in jpeg, however it was and the upload button did not work after I returned. The only way out was to start the process again, then came the message that the file name already existed and the button stopped working again. I started again and when I tried for the third time several weird codes appeared.
Can a moderator of that area check what happened and "clean up" the file name on my account? Because it seems the file name was stored there.

Thanks in advance.