After installing Ruby 2.2.0 and the latest version of passenger (as of this writing) 4.0.56 I started to get this error in nginx error.log:
symbol lookup error: /opt/rubies/ruby-2.2.0/lib/ruby/gems/2.2.0/gems/passenger-4.0.56/buildout/ruby/ruby-2.2.0-x86_64-linux/passenger_native_support.so: undefined symbol: rb_thread_blocking_region
After a quick google search I found phusion/passenger#1314 (comment).
I'm using ruby-install
so I re-installed the Ruby 2.2.0 using this command: