To undo a Git merge on your local repository, the approach depends on the current state of the merge:

🛑 Scenario 1: Merge in Progress (Uncommitted)

If you’ve initiated a merge but haven’t committed yet, and want to cancel it:

git merge --abort

This command will stop the merge process and revert your working directory to the state before the merge began.([Git Scripts][1])

✅ Scenario 2: Merge Committed Locally (Not Pushed)

If you’ve completed the merge and committed it locally but haven’t pushed to the remote repository:

git reset --hard HEAD~1

This command resets your current branch to the commit before the merge, effectively removing the merge commit and any changes introduced by it. Be cautious: this will discard any uncommitted changes in your working directory.([GeeksforGeeks][2])

🔁 Scenario 3: Merge Committed and Pushed to Remote

If the merge has been committed and pushed to the remote repository, it’s safer to create a new commit that undoes the changes introduced by the merge:([Warp][3])

git revert -m 1 <merge_commit_hash>
  • Replace <merge_commit_hash> with the hash of the merge commit you want to revert.
  • The -m 1 option specifies that you want to keep the changes from the first parent of the merge (usually the branch you merged into).([Codedamn][4], [git-tower.com][5])

This approach preserves the history and is recommended when the merge has been shared with others.

🧭 Finding the Merge Commit Hash

To identify the hash of the merge commit you wish to undo:

git log --oneline

Look for the commit message associated with the merge to find its hash.

⚠️ Important Considerations

  • Avoid using git reset on public/shared branches unless you’re certain that no one else is working on them, as it rewrites history and can cause issues for collaborators.
  • Always ensure you have backups or have pushed your changes to a remote repository before performing operations that alter commit history.