Git: index file open failed: Permission denied on "git status". Hosted on Bitbucket

Got the same error fatal: index file open failed: Permission denied by run git status, and I checked .git/index by

$ ls -al .git/index

to my surprise, it's

----------  1 Kjuly  staff  768248 Sep  2 11:07 .git/index

I've no idea why & how it changed. Anyway, after I changed it's permission back to 644 by

$ chmod 644 .git/index

git status works.

Make sure the .git directory and its files/subdirectories are owned and writable by your user. This sounds like the repository was either cloned under a different user account or as root user (e.g. through sudo).

It does not matter where the remote of the repository is hosted, git status only accesses the local repository.