fatal: A branch named ... already exists

Common causes

• You already created this branch previously
• You're trying to create a branch from a different starting point but the name is taken
• A teammate's branch was fetched and shows up as a remote tracking ref with the same name
• A script or automation created the branch before you ran the command

How to fix it

1. Switch to the existing branch: git checkout <branch-name>
2. List all branches to see what exists: git branch -a
3. Delete the old branch if it's safe: git branch -d <branch-name>, then create a new one
4. Use a different name: git checkout -b <new-unique-name>

Example

Running git checkout -b feature/login when that branch was already created