As the exception message says, “Database may be already in use”. You need to close all other connection(s), to make sure the database is not open in another process concurrently.
By the way, don’t use AUTO_SERVER=TRUE and the server mode at the same time. See the documentation for the automatic mixed mode. Use either one.
I guess you are a bit confused about the different connection modes. I suggest to read the documentation about the connection modes, to make sure you understand it.