git subtree error "fatal: refusing to merge unrelated histories"

14,820

Solution 1

This was a bug in git, it was fixed in https://github.com/git/git/commit/0f12c7d4d175bb0566208213b1b340b6794f305c

See also: https://www.spinics.net/lists/git/msg282340.html

Solution 2

If the subtree was added using --squash, you need to also use --squash when you pull

git subtree pull --prefix=<folder-goes-here> <remote-goes-here> <branch-goes-here> --squash

Solution 3

I've been struggling with this for a while and think I found the solution.

I'm pretty new to git so forgive me if I use the wrong names for things.

The problem may have come from you using the --squash option when you ran the git subtree add command.

Try removing the subtree (remove the remote repository and delete all the local files, commit, and push). Then redo the subtree add without the --squash option.

I then jumped over to my subtree repository, made some changes, committed and pushed, then hopped back to my main superproject repository and did a git subtree pull. It gave me some error about the working tree having modifications. To get around that I did a git checkout master, then a git push, then tried the subtree pull again. It worked.

Hope that helps.

Solution 4

What worked for me was using git merge with subtree strategy:

git merge -s subtree -Xsubtree="$prefix" subremote/branch --allow-unrelated-histories

git subtree uses something similar to that under the hood.

Share:
14,820
Matthijs
Author by

Matthijs

Updated on June 21, 2022

Comments

  • Matthijs
    Matthijs almost 2 years

    I'm trying to figure out how 'git subtree' works. I've followed all directions on this page, but I always get an error trying to merge the subtree project in my own repo ('Step 2'): fatal: refusing to merge unrelated histories.

    I've read this post, and when I use the --allow-unrelated-histories option, it seems to work fine. However, I'm not sure whether I should use this...My impression is that the whole point of subtrees is to have unrelated histories within one repository, so it feels strange to have to add the option. Should I add it nevertheless, or am I doing something wrong?

    I'm using git v2.9.3 on osx 10.11.6

  • joeybladb
    joeybladb over 6 years
    What git version did this finally make it into?
  • ZachB
    ZachB over 5 years
    That particular commit landed in git v2.9.3 and AFAICT is not the solution to the OP's issue. It affects the behavior of --rejoin, which only applies to the subtree split command.
  • Benoit Duffez
    Benoit Duffez about 5 years
    Squash is a useful option when retrieving a large repo. Removing the subtree and adding it back without the subtree can be avoided by using @PencilBow's solution.
  • Cameron
    Cameron almost 5 years
    Thanks! This was my issue as I had apparently copied the folder from another project