Git Error on Git Pull (Unable to Update Local Ref)

My team and I ran into this error, unable to update local ref, when doing a pull in SourceTree.

Update 2020: Per @Edward Yang's answer below, @bryan's comment on this answer, and this question/answer you may need to run both git gc --prune=now and git remote prune origin. Running only the former has always worked for me but based on ppl's responses I think both are necessary to address different causes of the error.

We used:

git gc --prune=now

This removes any duplicate reference objects which should fix the issue.

Here are a few links where you can learn more about git references and pruning :

git tip of the week

git-prune documentation

git references

I solved as below:

git remote prune origin

with gitbach line commande, use git update-ref to update reference of your local branch:

$ git update-ref -d refs/remotes/origin/[locked branch name]

then pull using $ git pull

[locked branch name] is the name of the branch that the error is happening because of mismatch of commit Ids.

Try to use this command in your git repository root folder:

rm .git/logs/refs/remotes/origin/master 

rm .git/refs/remotes/origin/master

It works to me!

Problem

Windows users can often have this problem

git pull 

gives the error: error: cannot lock ref unable to update local ref