Thanks, Tracy!
We have upgraded our test-server from 2.0.3 to dotLRN 2.1 and will spend next days on testing.
For all people using external authentification (auth-pam):
This package is not contained in dotLRN-tarball.
Because of a change in a function call in "acs-authentication", you will have to upgrade "auth-pam"-package, too.
You can check out latest version by changing into package dir and typing:
cvs -d:pserver:mailto:anonymous@openacs.org:/cvsroot co auth-pam
(-d:... for tarball-users)
If you have forgotten to do this before starting upgrade and you can't login: just checkout as mentioned above and reboot your server.