I am using Postgres on macOS Big Sur for development.
The database doesn't require any credentials.
When I try to connect without Userid, I get the message: "An error occurred while establishing the connection:
FATAL: no PostgreSQL user name specified in startup packet"
How do I connect to my Database?
(Using the user "postgres" doesn't work either.
Sorry for the late answer.
If this is still a problem please Please enable Debug DbVisualizer in Tools->Debug Window and the Debug tab and then re-run the operation that causes the issue. Then use Help->Contact Support in DbVisualizer to send the log file to us (make sure that is checked).