How do I resolve 'brew update' failures from failed fetch behind an authenticated firewall

Question

I recently tried to update brew and received these errors:

% brew update
cat: /usr/local/Homebrew/.git/TMP_FETCH_FAILURES: No such file or directory
Error: Fetching /usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask failed!
Fetching /usr/local/Homebrew/Library/Taps/aws/homebrew-tap failed!
Fetching /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core failed!
Fetching /usr/local/Homebrew failed!

I'm not sure why these are failing?

Answer 1

This could be due to your git proxy being misconfigured. In my case, the http proxy requires authentication, but my git proxy configuration only had the user name, not the password. To resolve it, I added the following to my ~/.zshrc file:

export PROXY=http://$PROXY_USERNAME:$PROXY_PASSWORD_URL_ENCODED>@<proxy-host>:8000
git config --global http.proxy $PROXY

After which, brew update completed successfully.

% brew update
Updated 3 taps (homebrew/core, homebrew/cask and aws/tap).
==> New Formulae
...
You have 37 outdated formulae installed.
You can upgrade them with brew upgrade
or list them with brew outdated.