fatal: Unable to create

fatal: Unable to create '/c/git_repo/.git/index.lock': File exists.

If no other git process is currently running, this probably means a
git process crashed in this repository earlier. Make sure no other git
process is running and remove the file manually to continue.

If you get the above fatal error when you are trying to run a git command like git checkout branch-name on your command line or terminal, well then you need to delete the index.lock file located under .git/ directory.

How to resolve fatal: Unable to create '/c/git_repo/.git/index.lock': File exists.

1. Go to your git repository directory,
2. now type cd .git,
3. Now type rm-f index.lock if you are using Linux/macOS
4. or type del index.lock if you are using Windows
5. Now try your command it should work

$ git checkout master
M       hello.py
A       myfile.py
A       Sample.java
Switched to branch 'master'
$