$ brew update fatal: could not read Username for 'https://github.com': terminal prompts disabled fatal: could not read Username for 'https://github.com': terminal prompts disabled Error: homebrew/homebrew-dupes does not exist! Run `brew untap homebrew/homebrew-dupes` to remove it. homebrew/homebrew-versions does not exist! Run `brew untap homebrew/homebrew-versions` to remove it.
After trying to fix the gitconfig in my local I found out that actually brew was the issue.
For me homebrew-dupes and homebrew-versions caused the problem. But the fix is similar to taps.
which gives you
... homebrew/dupes homebrew/versions ...
a simple untap
brew untap homebrew/dupes brew untap homebrew/versions
after which everything is ok
brew update Already up-to-date.