The error is indicating that it isn't connecting to the server. There's nothing in the logs indicating that the calls to perforce are getting a valid P4PORT and they aren't being sent command-line arguments.
Double-check that your Source Code Management
plugin in your Job is configured as you expect it to be. The P4PORT
should be coming from Jenkins immediately before the first p4
command is generated (although it won't appear in the logs).
Generally "Unable to check workspace against depot" is a valid diagnostic. If you get "Workspace does not exist", that may be bogus, due to a number of factors, but the "Unable to check" error tends to indicate that a connection can't be made or there is an authentication failure.
If you are using SSL, make sure you put that in the connection string as well (ssl:mysql:1667
as an example), since that will cause a connection failure, although it should generate a different message in the logs.