Recently on CURRENT, I did a pkg upgrade, and of course, this was the time I didn't use bectrl to back up. So, I couldn't login as user afterwards.It turned out that bash, which I use (as well as zsh, but not csh) was missing a shared object. In the end, I fixed it by doing ln -s <library>.so <library>.so.9. (Not on that machine at the moment, so can't tell you which library. But, if something like that happens, where you can log in as root, but not user, login as root, then just run
zsh
or whatever shell you're using, and you may find that like me, you get a useful error like can't load library whatever. Then you can change your user's shell to say, sh (which is what I did) or work as root to try to fix the problem. (X also stopped working, saying the module isn't recognized by the kernel, but as this was an unimportant install, I may just give up and reinstall once I get back from a trip I'm on. This is CURRENT, so not asking for help, just mentioning this as a reason people can't log in as user after an upgrade.)