Error installing debugger-linecache in Ruby 1.9.3

this may help you, it works for me

gem install debugger-linecache -v '1.1.2' -- --with-ruby-include=$rvm_path/src/ruby-1.9.3-p286/

This error means that the selected version of debugger does not support your current Ruby version. There are two solutions:

1. Update the debugger gem via bundle update debugger. New versions of debugger are backward-compatible with old Ruby versions, so this is the best way to fix it.
2. Downgrade your Ruby version.

Update/Install the gem debugger-ruby_core_source,

gem install debugger-ruby_core_source

it has been corrected here : https://github.com/cldwalker/debugger-ruby_core_source/pull/7