Sometimes you get the following error while trying to pull updates from remote repoistory:
fatal: refusing to merge unrelated histories
You have cloned a project and, somehow, the .git directory got deleted or corrupted. This leads Git to be unaware of your local history and will, therefore, cause it to throw this error when you try to push to or pull from the remote repository.
You have created a new repository, added a few commits to it, and now you are trying to pull from a remote repository that already has some commits of its own. Git will also throw the error in this case, since it has no idea how the two projects are related.
--allow-unrelated-histories flag to enforce pulling, For Example:
git pull origin master --allow-unrelated-histories