error: Your local changes to the following files would be overwritten by merge:
    src/app.js
Please commit your changes or stash them before you merge.

You have uncommitted changes in files that Git needs to modify (from a pull, merge, or checkout). Git refuses to overwrite your work.

Fix 1: Stash your changes, then pull

git stash
git pull
git stash pop

This saves your changes, pulls the new code, then re-applies your changes on top. If there are conflicts, you’ll need to resolve them.

Fix 2: Commit your changes first

git add -A
git commit -m "WIP: save current work"
git pull

Then you can amend or squash the commit later if needed.

Fix 3: Discard your local changes (if you don’t need them)

# Discard changes in specific files
git checkout -- src/app.js

# Discard ALL uncommitted changes
git checkout -- .

# Nuclear option: reset everything
git reset --hard
git pull

⚠️ git reset --hard permanently deletes uncommitted changes. Make sure you don’t need them.

Fix 4: For checkout/branch switching

# ❌ Can't switch branches with uncommitted changes
git checkout feature-branch

# ✅ Stash first
git stash
git checkout feature-branch
git stash pop  # Re-apply on the new branch

Related resources

• Git cheat sheet
• Git complete guide