長いこと更新作業を忘れるとでやすいエラーです. $ brew update error: The following untracked working tree files would be overwritten by merge: Library/Formula/cabocha.rb Please move or remove them before you can merge. Aborting Updating 7d2c1da..bfe50e3 Error: Failed while executing git pull origin refs/heads/master:refs/remotes/origin/master 対策の詳しいことは下記のサイトから brew update fails · Issue #5128 · Homebrew/legacy-homebrew ·