After more investigating and experimenting, it appears that mysql_password value in /etc/gromox/adapter.cfg is not being parsed correctly.
However, when looking at (https://github.com/grommunio/gromox/blob/master/tools/adaptor/main.cpp), the way the config file is parsed states (line 78):
strtol(pconfig->get_value("mysql_port"), nullptr, 0),
Thus when reading the config file, the token it is looking for is mysql_passwd and not mysql_password as the documentation states. I'm opening a github issue about this, as once I made the change the errors disappear:
For the time being, if you edit /etc/gromox/adapter.cfg and change mysql_password to mysql_passwd this should get rid of these errors. Be sure to restart gromox-adapter after making the changes.
I'm new to Grommunio - only just installed it last night, so please excuse me if I am wrong.