After I updated macOS Catalina, Markdown Preview no longer works. I got the following error message:
After I ran the above command, I received the following error message from the Terminal:
$ /usr/bin/gem install --user redcarpet pygments.rb
Building native extensions. This could take a while...
ERROR: Error installing redcarpet:
ERROR: Failed to build gem native extension.
current directory: /Users/tzha/.gem/ruby/2.6.0/gems/redcarpet-3.5.0/ext/redcarpet
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/ruby -I /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0 -r ./siteconf20191111-836-11oqvm2.rb extconf.rb
mkmf.rb can't find header files for ruby at /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/include/ruby.h
You might have to install separate package for the ruby development
environment, ruby-dev or ruby-devel for example.
extconf failed, exit code 1
Gem files will remain installed in /Users/tzha/.gem/ruby/2.6.0/gems/redcarpet-3.5.0 for inspection.
Results logged to /Users/tzha/.gem/ruby/2.6.0/extensions/universal-darwin-19/2.6.0/redcarpet-3.5.0/gem_make.out
Successfully installed pygments.rb-1.2.1
Parsing documentation for pygments.rb-1.2.1
Done installing documentation for pygments.rb after 0 seconds
1 gem installed