Home Brew install package getting could not resolve HEAD to a revision

Question

I just installed the latest homebrew with version Homebrew 2.7.3. I have git pre-install on my Mac OS, and I was trying to install brew install git-crypt & brew install git-gui and getting an error on fatal: Could not resolve HEAD to a revision. It looks like it failed on any packages.

==> Searching for similarly named formulae...
Error: No similarly named formulae found.
Error: No available formula or cask with the name "git-crypt".
==> Searching for a previously deleted formula (in the last month)...
Error: No previously deleted formula found.
==> Searching taps on GitHub...
Error: No formulae found in taps.

I tried uninstall then re-install homebrew using their command line : https://github.com/homebrew/install#uninstall-homebrew

By running brew doctor, I am getting some warnings :

Warning: "config" scripts exist outside your system or Homebrew directories.
`./configure` scripts often look for *-config scripts to determine if
software packages are installed, and which additional flags to use when
compiling and linking.

Having additional scripts in your path can confuse software installed via
Homebrew if the config script overrides a system or Homebrew-provided
script of the same name. We found the following "config" scripts:
  /Library/Frameworks/Python.framework/Versions/3.8/bin/python3-config
  /Library/Frameworks/Python.framework/Versions/3.8/bin/python3.8-config

Warning: Some taps are not on the default git origin branch and may not receive
updates. If this is a surprise to you, check out the default branch with:
  git -C $(brew --repo homebrew/core) checkout master

I checked this directory

/usr/local/Homebrew/Library/Taps/homebrew/homebrew-core

and realize there's no Formula folder.

Any help would be appreciate.

Answer 1

I had this error and solved with

git -C $(brew --repo homebrew/core) checkout master