Thats what I found as well, but my backup folder has no spaces in it, or its parent folders. It used to work fine, but as of 3 days ago this error started to show up. Here is the folder path I use:
I’m not sure this will work, but it might help to turn on Webmin’s Debug Logging, and hope it will record the exact SCP command it tries to execute. That might give a hint as to why it fails with the odd error message.
Found the cause when it decided to start working randomly, seems to be a webmin error
When using variables in the name, when %e is like the first, it seems to insert a space " 1" instead of “1” or “01” and this seems to break it. Where would I submit this error?