357 
develop branch --> dashboard (working branch)

I use git merge --no-ff develop to merge any upstream changes into dashboard

git log:

commit 88113a64a21bf8a51409ee2a1321442fd08db705 Merge: 981bc20 888a557 Author: XXXX <> Date: Mon Jul 30 08:16:46 2012 -0500 Merge branch 'develop' into dashboard commit 888a5572428a372f15a52106b8d74ff910493f01 Author: root <[email protected]> Date: Sun Jul 29 10:49:21 2012 -0500 fixed end date edit display to have leading 0 commit 167ad941726c876349bfa445873bdcd475eb8cd8 Author: XXXX <> Date: Sun Jul 29 09:13:24 2012 -0500

The merge had about 50+ commits in it, and I am wondering how to just revert the merge so dashboard goes back to the state pre-merge

The second part of this is, if I dont do merge with --no-ff, I don't get the commit 'Merge branch 'develop' into dashboard' .. How would I roll that merge back?

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    Possible duplicate of Undo a Git merge?. Commented Jul 7, 2014 at 4:45

6 Answers 6

Reset to default
496

Reverting a merge commit has been exhaustively covered in other questions. When you do a fast-forward merge, the second one you describe, you can use git reset to get back to the previous state:

git reset --hard <commit_before_merge>

You can find the <commit_before_merge> with git reflog, git log, or, if you're feeling the moxy (and haven't done anything else): git reset --hard HEAD@{1}

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14 Comments

thanks for the quick reply .. looking at git log, the commit before the merge is 50+ commits back, as the git merge develop actually puts in all the other commits. I guess what I dont get is, if I dont know what/where that merge was - how do I find it? You mention finding the commit_before_merge .. I guess I am not understanding that part
looks like with git reflog looks like it summarizes the last heads nicely, and allows me to know where I need to reset to. git log seems to have too much granularity to pinpoint the place to reset to. Thanks
Yeah, reflog's a lifesaver. HEAD@{1} just describes the second most recent state of HEAD, or more technically: "A ref followed by the suffix @ with an ordinal specification enclosed in a brace pair (e.g. {1}, {15}) specifies the n-th prior value of that ref."
What about pushing the revert to remote? I don't see how it will work.
This is hopeless. It destroys all commits after the merge.
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233

From here:

http://www.christianengvall.se/undo-pushed-merge-git/

git revert -m 1 <merge commit hash>

Git revert adds a new commit that rolls back the specified commit.

Using -m 1 tells git that this is a merge and we want to roll back to the parent commit on the master branch. You would use -m 2 to specify the develop branch.

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5 Comments

Note that you cannot re-merge the branch after this, as the docs says: "Reverting a merge commit declares that you will never want the tree changes brought in by the merge. As a result, later merges will only bring in tree changes introduced by commits that are not ancestors of the previously reverted merge. This may or may not be what you want."
@DaliborKarlović That statement is a bit harsh. You can definitely bring back those changes later, the trick is to revert the revert commit. More info here in the section "Reverting the revert"
Sadly, the here link in the @Hilikus comment is no longer valid. The site claims the content got moved to a book ( git-scm.com/book/en/v2 ) but if so, it is non-trivial to locate in there.
@DaliborKarlović is this the case wkth the answer above from @Christopher?
The undoing merges content was moved to here
50

Just reset the merge commit with git reset --hard HEAD^.

If you use --no-ff git always creates a merge, even if you did not commit anything in between. Without --no-ff git will just do a fast forward, meaning your branches HEAD will be set to HEAD of the merged branch. To resolve this find the commit-id you want to revert to and git reset --hard $COMMITID.

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3 Comments

Good solution if you don't know the commit before the merge.
Worked for me as i don't know commit id.+1
if the unwanted merge was already committed to remote, I used git push -f to update remote branch after reverting.
30 
git revert -m 1 88113a64a21bf8a51409ee2a1321442fd08db705

But may have unexpected side-effects. See --mainline parent-number option in git-scm.com/docs/git-revert

Perhaps a brute but effective way would be to check out the left parent of that commit, make a copy of all the files, checkout HEAD again, and replace all the contents with the old files. Then git will tell you what is being rolled back and you create your own revert commit :) !

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7 Comments

+1 because this answer does not mess with the history as reset does (really important if you already pushed to remote). But what unexpected side-effects should I expect?
Is this the side-effect you mentioned? Reverting a merge commit declares that you will never want the tree changes brought in by the merge. As a result, later merges will only bring in tree changes introduced by commits that are not ancestors of the previously reverted merge. This may or may not be what you want.
You say git reset is the solution, but also mention that it might have unexpected side-effects. However, that link is from git revert, not git reset :)
Please note, git reset does not have an -m flag. Also note @JorgeOrpinel references the git-revert docs, not git-reset. I think he meant to say git revert not git reset
How to avoid Mainline was specified but commit 1234xyz is not a merge error.
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5

If you merged the branch, then reverted the merge using a pull request and merged that pull request to revert.

The easiest way I felt was to:

  1. Take out a new branch from develop/master (where you merged)
  2. Revert the "revert" using git revert -m 1 xxxxxx (if the revert was merged using a branch) or using git revert xxxxxx if it was a simple revert
  3. The new branch should now have the changes you want to merge again.
  4. Make changes or merge this branch to develop/master
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0

if it is just a last commit you can simply do git reset --hard HEAD

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