there was an error during the CUPS operation server error internal error

[Valtam]

I have the same issue adding a printer, but I expect no replies either.

Ouch! The internet is littered with support forums that don't have replies, even on the big boys. Not sure why you've chosen to respond to a thread from June.
There's no reply here, because if you look at their profile, they're running 'Linux Lite: 3.8 64bit'. That is unsupported, period!