Can't run Homebrew anymore I've been installing packages using Homebrew until now. I just found that I can't even run homebrew basic commands:
$ brew --version
Traceback (most recent call last):
    4: from /usr/local/Homebrew/Library/Homebrew/brew.rb:13:in `&lt;main&gt;'
    3: from /usr/local/Homebrew/Library/Homebrew/brew.rb:13:in `require_relative'
    2: from /usr/local/Homebrew/Library/Homebrew/global.rb:10:in `&lt;top (required)&gt;'
    1: from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require': cannot load such file -- active_support/core_ext/object/blank (LoadError)

$ brew help
Traceback (most recent call last):
    4: from /usr/local/Homebrew/Library/Homebrew/brew.rb:13:in `&lt;main&gt;'
    3: from /usr/local/Homebrew/Library/Homebrew/brew.rb:13:in `require_relative'
    2: from /usr/local/Homebrew/Library/Homebrew/global.rb:10:in `&lt;top (required)&gt;'
    1: from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require': cannot load such file -- active_support/core_ext/object/blank (LoadError)

Looks like the application got corrupted or something, but at this point I'm not sure how to proceed. I have macOS Catalina latest Version 10.15.6 and recently upgraded Xcode to Rel.12
Thanks.
It looks like the Xcode12 install Command Line Tools which have newer ruby framework and your Brew version is not compatible with this one.