How to undo a git rebase ?

To undo a Git rebase, follow these steps depending on your situation:

1. Undo a Rebase in Progress (Before Completion)

If the rebase is ongoing (e.g., conflicts not resolved), abort it:

git rebase --abort

2. Undo a Completed Rebase

If the rebase finished but hasn’t been pushed, reset to the original state using ORIG_HEAD:

git reset --hard ORIG_HEAD

ORIG_HEAD points to the commit where HEAD was before the rebase started.

3. If `ORIG_HEAD` is Unavailable (e.g., Closed Terminal)

Use the reflog to find the commit before the rebase:

git reflog

Locate the entry like rebase (start): checkout <hash> or rebase (finish): ....
Reset to the commit before the rebase:

  git reset --hard <commit-hash>

4. Undo a Rebase That Was Pushed to Remote

If you’ve already pushed the rebased commits, force-push the original history:

git push origin <branch-name> --force
# Or safer (checks for remote changes):
git push origin <branch-name> --force-with-lease

Example Workflow

# 1. Start an interactive rebase (5 commits back)
git rebase -i HEAD~5

# 2. Realize you made a mistake and abort:
git rebase --abort

# If rebase already completed:
git reflog
# Find the pre-rebase commit (e.g., abc123)
git reset --hard abc123

# Force-push if already pushed to remote:
git push origin main --force-with-lease

Key Notes

ORIG_HEAD: Git automatically creates this reference during operations like rebase.
Force-Pushing: Use cautiously if others have pulled the rebased branch.
Lost Commits: If you can’t find the original commit in the reflog, use git fsck --lost-found to recover dangling commits.

Prevention Tips

Avoid rebasing public/shared branches.
Use git merge instead of git rebase for collaborative workflows.