And, yes, another question of a similar type but non of the postings have helped my situation. Been trying to solve this one for two days. When I type 'rails new app' or run 'bundle install' in an existing app, I get: Errno::EPERM: Operation not permitted - /Users/pb/.rvm/gems/ruby-1.9.2-p290/gems/json- 1.6.5/.gitignore An error occured while installing json (1.6.5), and Bundler cannot continue. Make sure that `gem install json -v '1.6.5'` succeeds before bundling. When I type any rails command in an existing project, I get: Could not find json-1.6.5 in any of the sources Run `bundle install` to install missing gems. When I type sudo gem install json -v '1.6.5' I get: Building native extensions. This could take a while... ERROR: Error installing json: ERROR: Failed to build gem native extension. /Users/pb/.rvm/rubies/ruby-1.9.2-p290/bin/ruby extconf.rb creating Makefile make /usr/bin/gcc-4.2 -I. -I/Users/pb/.rvm/rubies/ruby-1.9.2-p290/include/ruby -1.9.1/x86_64-darwin10.8.0 -I/Users/pb/.rvm/rubies/ruby -1.9.2-p290/include/ruby-1.9.1/ruby/backward -I/Users/pb/.rvm/rubies/ruby-1.9.2 p290/include/ruby-1.9.1 -I. -D_XOPEN_SOURCE -D_DARWIN_C_SO URCE -fno-common -O3 -ggdb -Wextra -Wno-unused-parameter -Wno-parentheses -Wpointer-arith -Wwrite-strings -Wno-missing-field-initializers -Wshorten-64-to-32 -Wno-long-long -fno-common -pipe -O3 -Wall -o parser.o -c parser.c make: /usr/bin/gcc-4.2: No such file or directory make: *** [parser.o] Error 1 I've tried all the following: Uninstall gem json (this tells me json is not installed) sudo gem update rails I've also installed the latest xCode - 4.2.1. Any advice as to solve my problem would be greatly appreciated!