Ignoring GEM because its extensions are not built
问题 On both my work and home computers, I recently upgraded Ruby to 2.3.1, using ruby-install . I use chruby as my Ruby switcher. I started seeing this warning in my terminal: Ignoring bcrypt-3.1.11 because its extensions are not built. Try: gem pristine bcrypt --version 3.1.11 Ignoring bcrypt-3.1.10 because its extensions are not built. Try: gem pristine bcrypt --version 3.1.10 Ignoring binding_of_caller-0.7.2 because its extensions are not built. Try: gem pristine binding_of_caller --version 0