[LE] Steam Upload Error 8

[TheWormpie]

I'm trying to upload a mod from the CK to Steam Workshop, but I keep receiving an error:

Failed to update the mod file on Steam! Steam error 8

Then on my workshop page on Steam, a new mod appears but with absolutely no information and no content...

 

I seem to recall to have experienced this before, but can't remember any way to fix it. Can anyone help?

 

Thanks in advance :)