How to fix Brew Error: Failed to link all completions, docs and manpages: Permission denied

The following error is pretty common when trying to update Homebrew on your Mac, with the brew update command:

Error: Failed to link all completions, docs and manpages: Permission denied

This is a permissions issue that can quickly be fixed with this command:

sudo chown -R $USER:admin /usr/local/*

The command tells your computer to allow admins (you) to modify all files in the /usr/local/ directory (* means all).

Because you’re using sudo you’ll be asked to type your system password to apply the change.

After typing your password and hitting enter, try running brew update again, and now it should work.