How to Fix Git MERGE_HEAD Error: Complete Guide

When you encounter the “You have not concluded your merge (MERGE_HEAD exists)” error, it means you started a merge operation but didn’t complete it - either by resolving conflicts and committing, or by aborting the merge entirely. The staged changes across multiple directories indicate Git successfully merged some files while leaving others with conflicts that need manual resolution.

Contents

• Understanding the Error
• Assessing Your Current State
• Solution Options
• Step-by-Step Resolution Process
• Handling Staged Changes
• Preventing Future Merge Issues

Understanding the Error

The “You have not concluded your merge (MERGE_HEAD exists)” error occurs when Git detects an active merge operation that hasn’t been completed. When you attempt a pull or merge, Git creates a MERGE_HEAD file in your .git directory to track the merge in progress. If you exit this state without properly completing or aborting the merge, Git will continue to show this error.

According to the Stack Overflow discussion, this typically happens when:

• You start a merge but encounter conflicts
• You resolve some conflicts but forget to commit
• You exit the merge process without proper cleanup

The staged changes you’re seeing across directories like app/assets, app/controllers, app/mailers, app/views, log/, and tmp/cache/assets/ are actually normal behavior during a merge with conflicts. Git automatically stages files that were successfully merged, leaving only the conflicting files for manual resolution.

Assessing Your Current State

Let’s examine your specific situation:

1. Branch divergence: Your branch ‘f’ has diverged from origin/master with 1 and 13 different commits respectively, indicating significant changes on both sides that need careful merging.

2. Multiple directories affected: The widespread staged changes suggest a comprehensive merge affecting many parts of your application.

3. Untracked files: These are files that exist in your working directory but haven’t been added to Git’s tracking system yet.

To get a clear picture of your current state, run:

git status
git log --oneline -5
git branch -vv

Solution Options

You have three main approaches to resolve this situation:

Option 1: Complete the Merge (Recommended if you want to keep the changes)

If you want to preserve the merge changes and resolve the conflicts:

1. Manually resolve any remaining conflicts
2. Stage the resolved files
3. Complete the merge commit

Option 2: Abort the Merge

If you want to discard the entire merge operation and return to the pre-merge state:

git merge --abort

Option 3: Reset and Redo

If you want to keep some changes but redo the merge process:

git reset --merge

Step-by-Step Resolution Process

Option 1: Complete the Merge

1. Identify remaining conflicts:

   bash

   git status
   

   Look for files marked as “unmerged” or containing conflict markers (<<<<<<<, =======, >>>>>>>)

2. Resolve conflicts manually:

   • Open each conflicting file in your editor
   • Remove conflict markers and choose the appropriate version of code
   • Save the files

3. Stage resolved files:

   bash

   git add <resolved-file>
   

4. Complete the merge commit:

   bash

   git commit -m "Merge branch 'f' into master"
   

   For Git versions 2.12 and above, you can also use:

   bash

   git merge --continue
   

5. Push to remote (if working with a shared repository):

   bash

   git push origin master
   

Option 2: Abort the Merge

1. Abort the current merge:

   bash

   git merge --abort
   

   This will reset your repository to the state before the merge attempt.

2. Verify clean state:

   bash

   git status
   

3. Reattempt the merge (optional):

   bash

   git pull origin master
   

Handling Staged Changes

The staged changes across multiple directories are normal during a merge with conflicts. Here’s how to manage them:

Understanding Staged Changes

As explained in the Atlassian Git tutorial, when a merge has conflicts, Git automatically stages files that were successfully merged, leaving only conflicting files for manual resolution.

Managing Staged Files

1. View staged changes:

   bash

   git diff --cached
   

2. Unstage specific files (if needed):

   bash

   git reset HEAD <file>
   

3. Remove from staging completely:

   bash

   git rm --cached <file>
   

4. Interactive staging (for partial changes):

   bash

   git add -p <file>
   

Handling Untracked Files

For untracked files in directories like log/ and tmp/cache/assets/:

1. Check what untracked files exist:

   bash

   git ls-files --others --exclude-standard
   

2. Add relevant files:

   bash

   git add <file>
   

3. Ignore unimportant files by adding them to .gitignore:

   log/*
   tmp/cache/assets/*
   

Preventing Future Merge Issues

To avoid similar situations in the future:

Best Practices

1. Always complete or abort merges: As noted in the TecAdmin guide, “always make sure to conclude your merges either by committing the merge or aborting it, especially before starting…”

2. Use smaller, focused branches: Break large changes into smaller, manageable commits to reduce merge complexity.

3. Regular pulls: Keep your local branch up to date with remote changes before starting new work.

4. Pre-merge checks: Always run git status before initiating a merge to ensure a clean working directory.

Advanced Techniques

1. Git rerere: Enable Git’s reusable merge resolution:

   bash

   git config --global rerere.enabled true
   

   As described in the Medium article, this remembers how you resolved conflicts in the past and applies those resolutions automatically.

2. Use merge tools: Configure Git to use external merge tools for conflict resolution:

   bash

   git config merge.tool kdiff3
   git config merge.conflictstyle diff3
   

Sources

1. You have not concluded your merge (MERGE_HEAD exists) - Stack Overflow
2. How to Fix Error: “You have not concluded your merge (MERGE_HEAD exists)”? - GeeksforGeeks
3. Git: You have not concluded your merge (MERGE_HEAD exists) - bobbyhadz
4. You Have Not Concluded Your Merge (MERGE_HEAD Exists) - Better Stack Community
5. You have not concluded your merge (MERGE_HEAD exists) – TecAdmin
6. How to Resolve Merge Conflicts in Git? - Atlassian Git Tutorial
7. Git merge conflict resolution shows staged changes which I didn’t do - Stack Overflow
8. Fix conflicts only once with git rerere - Medium

Conclusion

The “MERGE_HEAD exists” error is a common Git scenario that occurs when a merge operation is left incomplete. In your case with staged changes across multiple application directories and a diverged branch, you have several resolution options:

1. Complete the merge if you want to preserve the changes and resolve remaining conflicts manually
2. Abort the merge using git merge --abort to discard the entire operation
3. Reset and redo the merge process using git reset --merge

The staged changes you’re seeing are normal - Git automatically stages successfully merged files while leaving conflicts for manual resolution. Remember to handle untracked files appropriately and consider using .gitignore for build artifacts and logs.

To prevent future issues, always complete or abort merges before starting new operations, consider using smaller focused branches, and enable Git’s rerere feature to remember conflict resolutions. Regular maintenance and communication with your team about merge strategies will help keep your repository healthy and conflict-free.