for ubuntu… i needed to
sudo chmod g+r /var/lib/boinc/gui_rpc_auth.cfg
as well as sudo usermod -a -G boinc $USER
optional step, if you’re using a boinc account manager, the syntax for sending the password is single quotes if you have a complex password. it took me many hours to figure this out.
boinccmd --join_acct_mgr bam.boincstats.com actng 'Passw0rd!!!'
(change your username from actng to your username. no, Passw0rd!!! isn’t my password but yes that is considered complex enough to warranty single quotes around or it won’t work.)
after waiting you can try boinccmd --get_tasks to check if tasks are downloaded/uninitialized or executing