fatal: refusing to merge unrelated histories

Git won’t merge two branches that don’t share a common ancestor. This usually happens when you created a repo on GitHub with a README and then try to pull into a local repo that was initialized separately.

Fix: Allow unrelated histories

git pull origin main --allow-unrelated-histories

That’s it. Git will merge the two histories. You might get merge conflicts — resolve them normally.

For rebase:

git rebase origin/main --allow-unrelated-histories

When this happens

• You ran git init locally AND created the repo on GitHub with a README/license
• You’re combining two separate repos into one
• You changed the remote to a different repository

Prevention

When creating a new project, pick one:

Option A: Create on GitHub first, then clone:

# Create repo on GitHub (with README), then:
git clone https://github.com/user/repo.git

Option B: Create locally first, push to empty GitHub repo:

git init
git add -A
git commit -m "Initial commit"
git remote add origin https://github.com/user/repo.git
git push -u origin main

Don’t do both (init locally AND create GitHub repo with files).

See also: Git cheat sheet | Git push rejected fix