Upgrading your FileVault 2 encrypted Mac to Mountain Lion

One nice thing about using FileVault 2 to encrypt your Mac is that Apple’s OS installers are aware of how to work with a FileVault 2-encrypted Mac.* For example, you can upgrade from Mac OS X 10.7.4 to Mac OS X 10.8.0 on a FileVault 2-encrypted Mac using the same process that you would use on an unencrypted Mac.

* I had previously been wrong on the Internet about this subject.

Since this is a process that’s more easily shown than explained, I’ve made a five minute video showing the process as I saw it.

Here’s the procedure I used:

1. Logged into my FileVault 2 encrypted Mac
2. Launched Install OS X Mountain Lion.app from /Applications
3. Selected my boot drive and let it proceed with the upgrade.
   
4. The upgrade restarted the Mac.
   
5. The FileVault 2 pre-boot login screen appeared and I logged in.
   
6. The upgrade automatically proceeded after the FileVault 2 login screen
   
7. After the upgrade process finished, the Mac restarted.
   
8. The FileVault 2 pre-boot login screen appeared and I logged in.
   
9. I clicked the buttons to skip the Apple ID setup
   
10. I then verified that I was now on 10.8.0.

Note: The video has been edited to artificially reduce the amount of time the installers take to run. Run time of the pre-edited video was 41 minutes.