What does "fatal: bad revision" mean?

If you only want to revert a single file to its state in a given commit, you actually want to use the checkout command:

git checkout HEAD~2 myFile

The revert command is used for reverting entire commits (and it doesn't revert you to that commit; it actually just reverts the changes made by that commit - if you have another commit after the one you specify, the later commit won't be reverted).

I was getting this error in IntelliJ, and none of these answers helped me. So here's how I solved it.

Somehow one of my sub-modules added a .git directory. All git functionality returned after I deleted it.

git revert doesn't take a filename parameter. Do you want git checkout?

I had a "fatal : bad revision" with Idea / Webstorm because I had a git directory inside another, without using properly submodules or subtrees.

I checked for .git dirs with :

find ./ -name '.git' -print