Git refusing to merge unrelated histories on rebase

During git rebase origin/development the following error message is shown from Git:

fatal: refusing to merge unrelated histories
Error redoing merge 1234deadbeef1234deadbeef

My Git version is 2.9.0. It used to work fine in the previous version.

How can I continue this rebase allowing unrelated histories with the forced flag introduced in the new release?

22 Answers

The default behavior has changed since Git 2.9:

“git merge” used to allow merging two branches that have no common base by default, which led to a brand new history of an existing project created and then get pulled by an unsuspecting maintainer, which allowed an unnecessary parallel history merged into the existing project. The command has been taught not to allow this by default, with an escape hatch --allow-unrelated-histories option to be used in a rare event that merges histories of two projects that started their lives independently.

See the Git release changelog for more information.

You can use --allow-unrelated-histories to force the merge to happen.

In my case, the error was just fatal: refusing to merge unrelated histories on every try, especially the first pull request after remotely adding a Git repository.

Using the --allow-unrelated-histories flag worked with a pull request in this way:

git pull origin branchname --allow-unrelated-histories

Try the following command:

git pull origin master --allow-unrelated-histories

This should solve your problem.

I got this error when I set up a local repository first. Then I went to GitHub and created a new repository. Then I ran

git remote add origin <repository url>

When I tried to push or pull, I got the same fatal: unrelated_histories error every time.

Here is how I fixed it:

git pull origin master --allow-unrelated-histories
git merge origin origin/master
... add and commit here...
git push origin master

For this, enter the command:

git pull origin branchname --allow-unrelated-histories

For example,

git pull origin master --allow-unrelated-histories

Reference:

GitHub unrelated histories issue

git pull origin <branch> --allow-unrelated-histories

You will be routed to a Vim edit window:

  • Insert commit message
  • Then press Esc (to exit “Insert” mode), then : (colon), then x (small “x”) and finally hit Enter to get out of Vim
  • git push --set-upstream origin <branch>

I had the same problem. Try this:

git pull origin master --allow-unrelated-histories 

git push origin master

I ran this command and issue got resolved.1

git pull origin branchName --allow-unrelated-histories

For Android Studio and IntelliJ:

First, commit everything and resolve any conflicts.

Then open the terminal from below of IDE and enter:

git pull origin master --allow-unrelated-histories

Now you can push.

Try git pull --rebase development

Two possibilities when this can happen –

  1. 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.

  2. 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.

SOLUTION

git pull origin master –allow-unrelated-histories

Ref – https://www.educative.io/edpresso/the-fatal-refusing-to-merge-unrelated-histories-git-error

WARNING THIS WILL POTENTIALLY OVERWRITE THE REMOTE REPOSITORY

This worked for me:

git push origin master --force

Since all the other answers are not actually answering the question, here is a solution inspired by this answer on a related question.

So you get your error doing git rebase:

$ git rebase origin/development
fatal: refusing to merge unrelated histories
Error redoing merge 1234deadbeef1234deadbeef

This error doesn’t actually cancel the rebase, but you are now in the middle of it:

$ git status
interactive rebase in progress; onto 4321beefdead
Last command done (1 command done):
   pick 1234deadbeef1234deadbeef test merge commit

So you can now do the merge by hand. Find out the parent commits of the original merge commit:

$ git log -1 1234deadbeef1234deadbeef
commit 1234deadbeef1234deadbeef
Merge: 111111111 222222222
Author: Hans Dampf
Date:   Wed Jun 6 18:04:35 2018 +0200

    test merge commit

Find out which of the two merge parents is the one that was merged into the current one (probably the second one, verify with git log 222222222), and then do the merge by hand, copying the commit message of the original merge commit:

$ git merge --allow-unrelated 222222222 --no-commit
Automatic merge went well; stopped before committing as requested
$ git commit -C 1234deadbeef1234deadbeef
[detached HEAD 909af09ec] test merge commit
 Date: Wed Jun 6 18:04:35 2018 +0200
$ git rebase --continue
Successfully rebased and updated refs/heads/test-branch.

I had the same problem. The problem is remote had something preventing this.

I first created a local repository. I added a LICENSE and README.md file to my local and committed.

Then I wanted a remote repository so I created one on GitHub. Here I made a mistake of checking “Initialize this repository with a README”, which created a README.md in remote too.

So now when I ran

git push --set-upstream origin master

I got:

error: failed to push some refs to 'https://github.com/lokeshub/myTODs.git'
hint: Updates were rejected because the tip of your current branch is behind
hint: its remote counterpart. Integrate the remote changes
(e.g. hint: 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.

Now to overcome this I did

git pull origin master

Which resulted in the below error:

From https://github.com/lokeshub/myTODs
branch            master     -> FETCH_HEAD
fatal: refusing to merge unrelated histories**

I tried:

git pull origin master --allow-unrelated-histories

Result:

From https://github.com/lokeshub/myTODs
 * branch            master     -> FETCH_HEAD
Auto-merging README.md
CONFLICT (add/add): Merge conflict in README.md
Automatic merge failed;
fix conflicts and then commit the result.

Solution:

I removed the remote repository and created a new (I think only removing file README could have worked) and after that the below worked:

git remote rm origin
git remote add origin https://github.com/lokeshub/myTODOs.git
git push --set-upstream origin master

This usually happens when you commit first time to remote repository. As error clearly says “refusing to merge unrelated histories”, we need to use –allow-unrelated-histories flag.

git pull origin master  --allow-unrelated-histories

Now there would be some conflicts which we have to solve manually. After that just commit the code and push it.

Firstly pull the remote changes to your local using the following command:

git pull origin branchname --allow-unrelated-histories

** branchname is master in my case.

When the pull command done, conflict occurs. You should solve the conflicts. I use Android Studio to solve conflicts. enter image description here

When conflicts solved, merge is done!

Now you can safely push.

I struggled with this as well, but I managed to find a workaround.

When you run into the error above, just cherry-pick the merge commit and then continue the rebase:

git cherry-pick -m 1 1234deadbeef1234deadbeef
git rebase --continue

When doing a git pull, I got this message fatal: refusing to merge unrelated histories for a repo module where I hadn’t updated the local copy for a while.

I ran this command just to refresh local from origin. I just wanted latest from remote and didn’t need any local changes.

git reset --hard origin/master

This fixed it in my case.

I tried git pull --allow-unrelated-histories didn’t work, but what solves this issue for me was:

  1. I copied all the files on my desktop repository to another folder and then deleted the folder.

  2. Then I clone the repo again because it is a new project.

  3. When I copied my files again and push it worked like charm.

For Googlers:

If you created a new repo on GitHub and accidentally initialized it with README or .gitignore files.

If you found yourself unable to merge or rebase because .git folder got corrupted.

Then:

  • Create a new folder
  • git clone
  • Paste all your files into this folder

Now the local and remote will have “related histories” and will merge or rebase happily.

I am using the rebase for years and I had never encountered such a problem. However, your first problem is, that you try to do it directly on the remote branch development from the remote repository, called origin. That is literally wrong because rebase is a dangerous command, that restructures the git history. Having said that, you should first try on your local repository and pushing it only, if it works for you as expected.

So, my usual rebase workflow looks like following (but please keep in mind, that you should not use rebase on branches, which you are not the only one committee. For such branches, use simply merge and resolve conflicts, if applicable):

  1. make sure you have a clean working tree (no uncommit changes)
  2. checkout to the branch you want to rebase onto (for instance, let’s say it’s master; as a one-line command): git checkout master && git pull origin master && git checkout development
  3. Do the actual rebase: git rebase master
  4. If it’s done and everything works as expected, push it to your remote. For doing so, you need to force it, because the remote host already has the history in another order, the remote would answer with nothing to push. So, we need to say “my local version of the history is correct, overwrite everything on that remote branch using my local version of the history”: git push -f origin development

As I already mentioned, keep in mind, that rebase manipulates the git history, that is usually a bad thing. However, it’s possible to do that on branches, where no one else commits to. In order to keep the branch pull-able for the other developers, use another merge strategy like merge itself, squash or cherrypick. So, in other words: Rebase shouldn’t be your tool on distributed development. It works fine for you if you are the only one who works on this repository.

We use the feature branch strategy. In this, I usually use rebase in order to get the “updates” from the other developers, that happened in the meantime on the master branch. Doing so, it reduces the size of commits that are visible in a pull request. Therefore, it makes it easier for the code reviewer to see my changes made in this feature branch.

I see the most voted answer doesn’t solve this question, which is in the context of rebasing.

The only way to synchronize the two diverged branches is to merge them back together, resulting in an extra merge commit and two sets of commits that contain the same changes (the original ones, and the ones from your rebased branch). Needless to say, this is a very confusing situation.

So, before you run git rebase, always ask yourself, “Is anyone else looking at this branch?” If the answer is yes, take your hands off the keyboard and start thinking about a non-destructive way to make your changes (e.g., the git revert command). Otherwise, you’re safe to re-write history as much as you like.

Reference: https://www.atlassian.com/git/tutorials/merging-vs-rebasing#the-golden-rule-of-rebasing

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