Same problem here.
Fresh installation inside zone on illumos/smartOS, all dependencies/needed modules installed and loaded (BTW: there is absolutely no proper dependency list; dependencies have to be extrapolated from the messy sudo-code-dump called “Installation Instructions”…)
When trying to register a new user, the form just fails with “error creating user”. No errors are logged by emoncms; no errors by apache; access log shows a successfull POST:
"POST /emoncms/user/register.json HTTP/1.1" 200
When creating a user manually in the db and using the password reset script, working accounts can be created; but for a real deployment this is completely useless.