I believe the recent homebrew update has somehow broken the pin function. Error messages are shown below when I execute brew cu pin firefox. Interestingly, firefox still gets pinned afterwards.
I had an error after brew cu update, then I continued to execute brew cu pin and also had your error, then I reopened the shell and re-executed and it was fine
I believe the recent homebrew update has somehow broken the pin function. Error messages are shown below when I execute
brew cu pin firefox
. Interestingly, firefox still gets pinned afterwards.