Git Merge Conflicts

What is a Merge Conflict?

A merge conflict happens when two branches change the same part of a file.

Git can't decide which change to keep, so you have to choose.

You must resolve the conflict before you can finish the merge.

Why Do Merge Conflicts Happen?

Merge conflicts usually happen when you merge branches that changed the same lines in a file.

This is common in collaborative projects or when working on long-lived branches.

How to See and Resolve Merge Conflicts

When you merge a branch and there are conflicting changes, Git will pause and mark the files with conflicts.

git merge feature-branch
Auto-merging filename.txt
CONFLICT (content): Merge conflict in filename.txt
Automatic merge failed; fix conflicts and then commit the result.

If there are conflicts, Git will tell you which files are affected.

See Which Files Have Conflicts

Use git status to see which files need your attention:

git status
On branch main
You have unmerged paths.
  (fix conflicts and run "git commit")
  (use "git merge --abort" to abort the merge)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
        both modified:   filename.txt

no changes added to commit (use "git add" and/or "git commit -a")

See the Differences

Use git diff to see what changed and help you decide how to resolve the conflict:

git diff
diff --cc filename.txt
index 56f2c83,0c6be20..0000000
--- a/filename.txt
+++ b/filename.txt
@@@ -1,1 -1,1 +1,5 @@@
++<<<<<<< HEAD
 +Your changes here
++=======
+ Other branch's changes
++>>>>>>> feature-branch

Edit the Conflict Markers

Open the conflicted file. You'll see sections like this:

<<<<<<< HEAD
Your changes here
=======
Other branch's changes
>>>>>>> feature-branch

Edit the file to keep what you want, then remove the conflict markers (<<<<<<<, =======, >>>>>>>).

Mark as Resolved

After fixing the file, mark it as resolved:

git add filename.txt

Complete the Merge

Finish the merge with a commit (if Git doesn't do it automatically):

git commit

Cancel the Merge

If you want to stop and undo the merge:

git merge --abort

Use a Visual Merge Tool

If you prefer, you can use a visual tool to resolve conflicts:

git mergetool

Pick One Side's Changes

If you want to keep only your changes or only the other branch's changes:

git checkout --ours filename.txt

git checkout --theirs filename.txt

Troubleshooting & Best Practices

• If you're stuck, you can always use git merge --abort to start over.
• Make sure you remove all conflict markers before marking as resolved.
• If you use git mergetool and don't like the result, you can still edit the files by hand.