API mismatch: nvidia kernel module
 

I did an update and an upgrade the other day and screwed something up.
Any suggestions on how I can fix this?

How did you apply the update?

And for the time being, you can boot from a previous version of the kernel.

Try to reboot

Kind regards

I did my normal apt-get update and apt-get upgrade.

Reboot has been done multiple times but I'll try again.

The error looks pretty specific:

Remove the installed nvidia module,then reinstall the current driver.

Not to sound like a complete and utter noob but how do I remove the nvidia module?

Well,you can do it manually with:

How did you install the driver originally?.

I believe I installed it the Debian way (http://wiki.debian.org/NvidiaGraphicsDrivers) way back and I think I then tried to update it via nvidia's actual driver.

The odd thing is, it was working fine the other day. Then I did my update/upgrade and rebooted and it didn't work.

I then followed the debian way to install the drivers again and it worked after I issued a startx but since last night it isn't working again.

That's the problem, probably. If you installed it the debian way, and then installed the driver from Nvidia's website, that explain why you have this mismatch. Try the following:

And then, attempt to start X again. If it doesn't work, then you probably have to uninstall the nvidia-glx package and reinstall it again the debian way (following the wiki link you posted).

You can't mix the Debian Nvidia packages and the installer you download from Nvidia themselves.
I would remove all Nvidia packages installed on the system and start from scratch,using one method.
This is why you are getting the error message you posted.

Yes, I also think that's the best thing to do (that means removing the nvidia-glx and the nvidia-kernel-* packages as well, besides the one from nvidia's website). :)

I just fixed it
 

This just happened to me. I'm using Ubuntu 12.04, and had installed the proprietary nvidia driver. Here's what I did:

I did an 'apt-get remove nvidia-*'. This removed all the nvidia drivers. I also noticed it uninstalled 'ubuntu-desktop'. I thought, wait a minute, I want ubuntu-desktop, so then I did an 'apt-get install ubuntu-desktop'. This installed as a dependency nvidia-common. at this point I rebooted, and voila I had graphics again.