You have uncommitted modifications to Homebrew/homebrew-core. If this is a surprise to you, then you should stash these modifications. Stashing returns Homebrew to a pristine state but can be undone should you later need to do so for some reason. git -C "/usr/local/Homebrew/Library/Taps/homebrew/homebrew-core" stash -u && git -C "/usr/local/Homebrew/Library/Taps/homebrew/homebrew-core" clean -d -f Uncommitted files: ?? Formula/o/[email protected]