Help with this error E_NOLOGIN_ACCESS

Is this on a site that was migrated from Joomla 1.0? That error is basically stating that the user isn't allowed to login. It's coming from the Joomla User plugin (not JFBConnect directly). That error is usually only shown in the admin area when a user has an account and they enter their credentials correct, but are not of the appropriate level (manager, admin, super admin) to access the area.

Hope this gives you a starting point for possible reasons. I don't know off the top of my head though.

I know you're integrated with JomSocial. Have you disabled their Facebook functionality? It shouldn't cause this issue, but it's a possible problem point.

Did you migrate or 'create' the users on the site? If you can take a look at the jos_users table for someone who can't get in, make sure that all the fields look correct. For a registered user, for instance, ensure that the following fields are setup like so:
usertype = "Registered"
block = 0
gid = 18

This is a strange issue, and really makes me think these user's were not created in a 'standard' way. Should be easy to fix them all up though, once we get to the bottom of the cause.

Very strange. Let us know if you see that again. It certainly shouldn't be happening when you link, or re-link accounts. We haven't heard of that problem before, but if it is something we're doing, we'll admit it's not good and will be right on top of fixing it.

Good luck!