How to Revert to a Previous Version of the Main Branch After Merging

Table of Contents

• Understanding the Scenario
• Step-by-Step Guide to Reverting
• Conclusion

When working with Git in a collaborative environment, merging branches is a common task. However, sometimes things go wrong, and you may need to revert to a previous version of the main branch after a merge. This guide will walk you through the process, ensuring you understand each step with real-world examples.

Understanding the Scenario

Imagine you have two branches in your Git repository: staging and main. The staging branch is where new features and changes are tested, while the main branch is the stable version of your codebase. You've recently merged a bunch of commits from staging to main, but something went wrong, and now the main branch is broken. Don't worry! Git makes it easy to revert to a previous version.

Before You Start

1. Check Your Branches: Make sure you're on the correct branch (main).
2. Backup: It's always a good idea to back up your current state, just in case.

git checkout main
git pull origin main

Step-by-Step Guide to Reverting

Step 1: Identify the Commit to Revert To

First, you need to find the commit hash (SHA) of the previous version of the main branch to which you want to revert. You can use the git log or git log --oneline command to list the commit history.

git log // or git log --oneline

Look for the commit before the merge that you want to revert to and copy its hash.

Step 2: Create a Backup Branch

Before making any changes, create a new branch from your current main branch. This acts as a safety net in case you need to revert the revert.

git checkout -b backup-main

Step 3: Revert the Main Branch

Now, you have two options to revert your main branch to a previous state: using git reset or git revert.

Option 1: Using Git Reset

This method is more straightforward but can be destructive if not used carefully. It changes the history of the branch.

git checkout main
git reset --hard <commit-hash>

// example
git reset --hard a1b2c3d4e5

Replace <commit-hash> with the hash you copied from the git log command.

Option 2: Using Git Revert

If you prefer to preserve the commit history, use git revert. This creates new commits that undo the changes made by the previous commits.

git checkout main
git revert -m 1 <merge-commit-hash>

// example
git revert -m 1 a1b2c3d4e5

Replace <merge-commit-hash> with the hash of the merge commit. The -m 1 flag indicates the mainline parent.

Step 4: Push Changes to Remote Repository

After reverting the changes locally, you need to push the updated main branch to the remote repository.

git push origin main --force

Note: Use --force with caution, as it rewrites the commit history.

Conclusion

Reverting to a previous version of the main branch after merging can seem daunting, but Git provides powerful tools to manage it. Whether you use git reset or git revert, you can confidently return your codebase to a stable state. Remember to back up your work, carefully identify the commit to revert to, and push your changes to the remote repository. By following these steps, you can keep your project on track and ensure that your main branch remains stable.

Happy coding!