I was getting this error when the ruby version is updated to 1.9.3-p484. When you’re using RVM, the solution is quite simple. Install the gem with the following command:
gem install debugger-linecache -v '1.1.2' -- --with-ruby-include=\$rvm_path/src/ruby-1.9.3-p484
If you need to install different version of debugger-linecache change 1.1.2 with appropriate version. If the you’re using different ruby version, change ruby-1.9.3-p484 to appropriate value.