When updating a certificate while the keyserver or WKD is not available I would expect an error message informing about the server being not available.

Instead the keyserver query returns "Invalid argument" or ""Server indicated a failure" and for WKD we show "The certificate was not found.":

I would expect some kind of "service not available" message.
Probably for both queries "Update failed: Server is not available."
The user then can check their internet connection or try again later, if the cause is that server is down at the moment.

Might have synergies with T7616.