How do I revert a merge commit that has already been pushed to remote?

General Discussions
#1

How do I revert a merge commit that has already been pushed to remote?

#2

In Git, when you perform a git revert on a merge commit (a commit with more than one parent), you need to specify which parent you want to revert to using the -m option. This is necessary because Git cannot automatically determine which parent was the mainline (the branch you want to revert to) and which branch was being merged.

When you view a merge commit in the git log output, you will see its parents listed under the “Merge” line. For example:

commit 8f937c683929b08379097828c8a04350b9b8e183

Merge: 8989ee0 7c6b236

Author: Ben James ben@example.com

Date: Wed Aug 17 22:49:41 2011 +0100

Merge branch ‘gh-pages’

Conflicts: README

In this case, git revert 8f937c6 -m 1 will revert to the tree as it was in commit 8989ee0, while git revert 8f937c6 -m 2 will revert to the tree as it was in commit 7c6b236.

Before performing the revert, it’s a good idea to use git diff to see the differences between the merge commit and its parents:

git diff 8989ee0 8f937c6

git diff 7c6b236 8f937c6

It’s important to note that by reverting a merge commit, you are declaring that you do not want any of the changes introduced by the merged commits.

This means that future merges will only bring in changes that are not ancestors of the reverted merge commit. This behavior may or may not be what you intend, so it’s important to understand the implications before reverting a merge commit.

#3

Reverting a merge commit in Git is straightforward. You can do it with the following command:

git revert -m 1 <commit-hash>

Replace <commit-hash> with the hash of the merge commit you want to revert. This command will create a new commit that undoes the changes made by the merge.

If you have permission to push directly to the master branch, you can push the revert commit directly to master. Otherwise, you can push it to a different branch (e.g., a revert branch) and create a pull request to merge it into master.

#4

Sometimes, the most effective way to rollback changes is to go back to a previous state and start fresh. Here’s how you can do it:

  1. Identify the commit you want to revert back to using git log. Note the full hash of the commit (the one before the mistake).

  2. Create a new branch from that commit:

    git checkout -b new-branch

    Replace <commit-hash> with the hash of the commit you want to revert back to.

  3. Delete the old branch and replace it with the new one:

    git branch -D old-branch git checkout -b old-branch new-branch

  4. If the changes have been pushed to a remote repository, delete the old branch from all repositories, push the new branch to the central repository, and pull it back down to all other repositories.

This approach allows you to effectively revert back to a previous state and continue your work from there.