git push fails with 'error: src refspec main does not match any' (or master). What does it mean and how do I fix it?

Cause: git push origin main tells Git to send the local branch named main. The error means there is no local branch (or ref) with that name. Common reasons: the repository has no commits yet (a branch doesn't really exist until the first commit), your local branch is called master but you typed main (or the other way round), a typo or wrong case in the branch name, or you're in detached HEAD. Fix: 1. See what you have: git branch (local branches; empty output means no commits yet) and git status (current branch, or 'No commits yet'). 2. No commits yet: add and commit something first: git add . && git commit -m "Initial commit", then git push -u origin main. 3. Branch name mismatch: push the branch you actually have (git push -u origin master), or rename it to match the remote's default: git branch -m master main, then git push -u origin main. On GitHub, the default branch name for new repositories is main; you can rename branches in the repository settings, and GitHub documents the steps for updating local clones afterwards. 4. To make new repositories start on main locally: git config --global init.defaultBranch main. 5. Detached HEAD: create a branch from where you are (git switch -c my-branch) and push that. Verify: git branch -vv shows your branch tracking origin/<name>, and git push succeeds. Sources: https://git-scm.com/docs/git-push https://docs.github.com/en/repositories/configuring-branches-and-merges-in-your-repository/managing-branches-in-your-repository/renaming-a-branch