The mistakes that fill Stack Overflow — Git

Every one of these has a Stack Overflow question with a million views. Here is what is actually happening in each, and the way out.

1. Committing a secret

You committed .env with a live API key. Deleting the file in a new commit does not help — the key is still in history, and anyone with the repository can read it.

If it is the most recent commit and not pushed:

git rm --cached .env
echo ".env" >> .gitignore
git commit --amend --no-edit

If it is deeper in history, rewrite it with git filter-repo:

pip install git-filter-repo
git filter-repo --invert-paths --path .env
git push --force-with-lease --all

Then tell every collaborator to re-clone. Their old clones still contain the secret.

Prevention: add .env to .gitignore in the first commit of every project, and install a pre-commit hook such as gitleaks that refuses commits containing credential patterns.

2. Force-pushing over a colleague

You rebased, pushed with --force, and erased three commits someone else had pushed.

They are not gone — they are in their reflog, and in the remote’s if you have server access:

# Ask your colleague to run:
git reflog
git push origin <their-hash>:refs/heads/rescue

Prevention: two things, both worth doing today. Use --force-with-lease always. And turn on branch protection for main on GitHub so force pushes are rejected at the server.

3. Detached HEAD

You are in 'detached HEAD' state...

This alarms people and it should not. It means HEAD points at a commit rather than a branch — usually after git checkout <hash> or during a bisect. Nothing is broken.

If you made no commits, just leave:

git switch -

If you made commits and want to keep them:

git switch -c rescue-branch      # name the work before moving

4. `git pull` produced a merge commit you did not want

Merge branch 'main' of github.com:org/repo

Default git pull merges. When both sides moved, you get this.

git reset --hard HEAD~1     # drop the merge (only if it is not pushed)
git pull --rebase           # do it again, rebasing

Prevention: the config from chapter two, git config --global pull.rebase true.

5. Committing a large binary

You committed a 300 MB file, removed it in the next commit, and the repository is still 300 MB bigger — forever, for everyone who clones it.

git filter-repo --strip-blobs-bigger-than 10M

Prevention: use Git LFS for large assets, and add a pre-commit hook rejecting oversized files. This one is much cheaper to prevent than to fix.

6. `git reset --hard` on work you needed

git reflog

a1b2c3d HEAD@{0}: reset: moving to HEAD~3
9f8e7d6 HEAD@{1}: commit: The work you thought you lost

git reset --hard HEAD@{1}

Recovered. The reflog keeps entries for 90 days by default.

7. Wrong author on your commits

You committed with the wrong user.email, so GitHub does not attribute the commits to you, or attributes them to the wrong account.

For the most recent commit:

git config user.email "right@example.com"
git commit --amend --reset-author --no-edit

For a range, git filter-repo with a mailmap, or interactive rebase with --exec.

Prevention: git config --list --show-origin | grep user. in every new repository before the first commit. This takes two seconds and it is the check that catches the work-versus-personal mix-up.

8. The merge conflict “resolved” into a bug

You picked a side to make the conflict go away, and quietly deleted a colleague’s change.

git log --merge -p path/to/file

This shows the commits from both sides that touched the conflicted file. Read them before choosing. A conflict is Git telling you that two intentions collided — resolving it is a judgement call, not a formatting exercise.

The habits that prevent most of this

Add .gitignore in your first commit, with .env in it
--force-with-lease, never --force
Branch protection on main, with force pushes disabled
git diff --staged before every commit
Commit early and often; clean up with interactive rebase afterwards
git status between every operation — it will usually tell you what to do next

Next: getting out of trouble when you are already in it.