thinlinc no password configured for vnc auth

Got hit by this problem after upgrading Thinlinc 4.4 to 4.6 on one of my Debian Jessie boxes.

After upgrade process and setup completed I ran commands to get around Debian issues as documented here:

sudo update-rc.d vsmagent defaults
sudo update-rc.d vsmserver defaults
sudo update-rc.d tlwebaccess defaults
sudo update-rc.d tlwebadm defaults
read thinlinc version < /opt/thinlinc/etc/thinlinc-release
/opt/thinlinc/bin/tl-config /vsm/setup_completed=${version}
sudo service vsmagent start
sudo service vsmserver start
sudo service tlwebaccess start
sudo service tlwebadm start

Then  I tried reconnecting to the session and Thinlinc client generated dreaded “No password configured for vnc auth”. Error is not particularly clear  and the only clue from Thinlinc mailing list was

Typically, this error message indicates "disk full" on the server and 
similar problems. The user could also be out of quota. It could also be an 
issue with SELinux. Basically, if Xvnc cannot access 
/var/opt/thinlinc/sessions/${USER}/X/sessionkey, you will get this 
error.

which wasn’t the case here.

What helped, I murdered all “tl-session” processes and restarted vsm*

pkill tl-session
systemctl restart vsmagent vsmserver

and after that Thinlinc was more keen to start a session for me. Jolly good.