Can't upload media content

Whenever I try to upload any media content (images, MP4s etc) the file starts to upload and then displays the message "Unable to connect to backend. Connection aborted." I've tried using different browsers (Chrome, Firefox, Edge) and the problem is the same on each. I've been able to upload files in the past, so I don't know what might have changed. Can anyone explain this error message?

Hi
if this has worked previously but isn't now it sounds like you need to contact whoever looks after your Xerte installation. There are no automated changes in Xerte itself that would have caused this so I would guess that either the server and/or the Xerte installation has been upgraded and resulted in a change of configuration or permissions etc.
HTH
Ron