Apple Mac OS X Not Accepting Login

So, there it is an Apple Mac configured to auto login is now showing a Login screen and it doesn’t seem to like any of the usernames and passwords that we could think of. In other words we’re locked out. I haven’t done an awful lot of Mac support, but I do know that it sits on top of a BSD core and because of this I knew we’d have some options. So, of course, the first thing I did was a quick search to try and get started… this post has a lot of helpful info about what to do if you’ve lost your administrator password (setting it up so you don’t have to enter a password for administrative tasks.) But most importantly it gave instructions for getting into single user mode.

CMD+S while the Mac is booting will trigger single user mode. If you see a black screen with a lot of text you’re in good.

The first thing I did was an fsck of the disk to try to determine if the drive was failing (my suspicion is that could be what caused the issue. Problems on the disk found and corrected. So, that sounds promising.

I browsed around to list the /user directory to make sure I knew the username for the primary user (ls /user ) and attempted to follow the instructions for starting Systemstarter which should launch NetInfo. The only problem is I didn’t see any information that looked promising. The instructions suggested to run niutil -list . /users but that didn’t return anything. Neither did passwd username give any means of actually changing the username. (That plugs into NetInfo.)

So, I started suspecting that there was a problem with netinfo and found a logfile in /var/log for netinfo…. yes it had problems trying to retrieve entries from the database.

So… at this point I had read this thread as well talking about problems with netinfo and the possibility of deleting (or renaming the netinfo folder), but I didn’t want to be so drastic to start with. So, I thought the suggestion of keeping the database and making it go through the new user setup to add a user to the existing database might be worth trying. My plan was to setup a new user and then from within the full running system try to change the password of the other user.

Well, I deleted /var/db/.AppleSetupDone and rebooted, walked through the setup of a new user and after the “getting more info” page it essentially hung and kept just a blank gray window on the page with a greyed out continue button and a back button.

So…. it was pretty convincing that the netinfo database was, to be technical, snarfed.

So, I went back into single user mode and this time I moved /var/db/local.nidb to /var/db/local.nidb.corrupted and rebooted. I must say I held my breath a bit, but I knew the files were still there in the /user directory for this user and if there were permissions problems I could fix them back at the command line…

So… I setup a new user and then used that to add the old user back into the netinfo database. It told me there was a folder with the same name and asked if I wanted to make use of that for the home for this user and again held my breath (afraid that it would wipe it clean…) but of course, it didn’t it just churned a few minutes and finished creating the user. I logged out and back in as the old user and everything was there and in good shape. Some things about the profile had reset to defaults (from what I had last seen.) I went back in and reconfigured auto-login for the user and all seemed to be set.

Oh, and we talked about making backups to a USB memory stick because Mac hard drives can fail JUST the same as PC hard drives.

So, what caused it? I have no clue… There had been some updates installed the two days before, but I don’t know that they would have damaged the netinfo database. I’m wondering if an abrupt power failure could have been the culprit, but I don’t know.

Here are a few (systemstartup) other (vim on mac reference), references I made use of (automated login howto).

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