With 2.0.1 we get:

$ maxadmin

WARNING: Unrecognised parameter 'user' in .maxadmin file

WARNING: Unrecognised parameter 'passwd' in .maxadmin file

Unable to connect to MaxScale at /tmp/maxadmin.sock: No such file or directory

This worked with MaxScale 1.4.3. It seems in 2.0.1 we have to specify the user and password on the command-line (after upgrade or if we do not rely on UNIX domain sockets only):

$ maxadmin --user=my_user --password=my_pw

WARNING: Unrecognised parameter 'user' in .maxadmin file

WARNING: Unrecognised parameter 'passwd' in .maxadmin file

MaxScale> 

As the old internet socket based communication was put back in 2.0.1, we should put back processing of user and passwd settings from .maxadmin.

Side note: This KB article:

https://mariadb.com/kb/en/mariadb-enterprise/reference-maxadmin/#configuring

also needs clarifications on what is supposed to be recognized in .maxadmin file and in what exact 2.0.x versions.