When I try to run `brew cleanup` I get:

Warning: Skipping atk: most recent version 2.34.1 not installed

Warning: Skipping git: most recent version 2.23.0_1 not installed

Warning: Skipping libgcrypt: most recent version 1.8.5 not installed

Warning: Skipping nspr: most recent version 4.23 not installed

Warning: Skipping nss: most recent version 3.46.1 not installed

Warning: Skipping poppler: most recent version 0.81.0 not installed

Error: Permission denied @ apply2files - /Users/iuliaulialiaia/Library/Caches/Homebrew/.cleaned

I can neither run other commands that uses `brew cleanup`, like `brew upgrade`:

...

==> `brew cleanup` has not been run in 30 days, running now...

Removing: /usr/local/Cellar/python@2/2.7.16... (3,750 files, 51.6MB)

Error: Permission denied @ apply2files - /Users/iuliaulialiaia/Library/Caches/Homebrew/.cleaned

P.S.: I cannot run homebrew as root:

Error: Running Homebrew as root is extremely dangerous and no longer supported.

As Homebrew does not drop privileges on installation you would be giving all

build scripts full access to your system.

User level:Level 9

At some point, I believe homebrew was suggesting one change the ownership and group of /usr/local to $(whoami):admin — which is what I have set (in Mojave) and homebrew just works for update, upgrade, and cleanup. A bit more of a PITA on Catalina though.

User level:Level 1

Guessing you are running Catalina then! It's changed the permissions model which has broken lots of stuff :(

This should work:

sudo chown -R $(whoami):admin /usr/local/* && sudo chomd -R g+rwx /usr/local/*

Then try brew cleanup

User level:Level 1

The second command has a typo, it should be chmod instead of chomd

sudo chown -R $(whoami):admin /usr/local/* && sudo chmod -R g+rwx /usr/local/*