Fixing MacOS Login Problems after 3Dconnexion Driver Installation

So I had a scary moment the other day: I hadn’t used my 3Dconnexion Space Pilot Pro in a while and suddenly had a need for it. For good measure, I thought: let’s update the drivers since it’s been a while. Well, that thought did cost me about two hours and a lot of nerves. After installing the driver and restarting the system, I could no longer log into my account. Booted up okay, was able to select account, enter password, progress bar … and then nothing. It got stuck when the progress bar was at its maximum.

Booting into safe mode (holding down shift key) didn’t work, probably because file vault disk encryption is active. Booting in verbose mode didn’t show anything useful either. My assumption was that the driver installed a kernel extension that broke the system, but how to remove it again?

Here is what I did (Disclaimer: this worked for me, might not work for you. Use at own risk):

1. Restart the system and boot into recovery mode (press hold CMD+R during startup).
2. Open Disk Utility. At this point, only the read-only recovery partition was mounted. Select the main system partition and press the mount button. This took a moment (didn’t seem to work at first) but at some point it asked me for my user password.
3. Quit Disk Utility, then choose “Terminal” from the top menu bar.
4. On the terminal, go to your main system partition (e.g. /Volumes/somethingsomething) and the to Library/Extensions.
5. In the folder, look for the 3Dconnexion.kext and move it to another place (for example the root folder of your main system partition /Volumes/somethingsomething).
6. Close terminal and restart the system.

After that, I could log into my account normally. I used the 3Dconnexion uninstall app in /Applications/3Dconnexion and then re-installed the driver. For some reason the installation (and restart) worked fine this time. Perhaps this is related to me not uninstalling the older drivers, who knows.

If YOU ever get locked out of your system because the login hangs, hope this will help you. If not sure what all the above means, seek help from a professional.