apache2 passenger puppetmaster 3.7.0

error.log

[ 2014-09-04 18:54:04.4660 11287/7f0691bfb700 Pool2/Implementation.cpp:883 ]: Could not spawn process for group /etc/puppet/rack#default: An error occured while starting up the preloader.
     in 'void Passenger::ApplicationPool2::SmartSpawner::handleErrorResponse(Passenger::ApplicationPool2::SmartSpawner::StartupDetails&)' (SmartSpawner.h:455)
     in 'std::string Passenger::ApplicationPool2::SmartSpawner::negotiatePreloaderStartup(Passenger::ApplicationPool2::SmartSpawner::StartupDetails&)' (SmartSpawner.h:566)
     in 'void Passenger::ApplicationPool2::SmartSpawner::startPreloader()' (SmartSpawner.h:206)
     in 'virtual Passenger::ApplicationPool2::ProcessPtr Passenger::ApplicationPool2::SmartSpawner::spawn(const Passenger::ApplicationPool2::Options&)' (SmartSpawner.h:752)
     in 'void Passenger::ApplicationPool2::Group::spawnThreadRealMain(const SpawnerPtr&, const Passenger::ApplicationPool2::Options&, unsigned int)' (Implementation.cpp:804)

[ 2014-09-04 18:54:04.4661 11287/7f068b7fe700 agents/HelperAgent/RequestHandler.h:2088 ]: [Client 20] Cannot checkout session.
Error page:
exit (SystemExit)
  /usr/lib/ruby/vendor_ruby/puppet/util.rb:502:in `exit'
  /usr/lib/ruby/vendor_ruby/puppet/util.rb:502:in `rescue in exit_on_fail'
  /usr/lib/ruby/vendor_ruby/puppet/util.rb:488:in `exit_on_fail'
  /usr/lib/ruby/vendor_ruby/puppet/application.rb:381:in `run'
  /usr/lib/ruby/vendor_ruby/puppet/util/command_line.rb:146:in `run'
  /usr/lib/ruby/vendor_ruby/puppet/util/command_line.rb:92:in `execute'
  config.ru:45:in `block in <main>'
  /usr/lib/ruby/vendor_ruby/rack/builder.rb:55:in `instance_eval'
  /usr/lib/ruby/vendor_ruby/rack/builder.rb:55:in `initialize'
  config.ru:1:in `new'
  config.ru:1:in `<main>'
  /usr/share/passenger/helper-scripts/rack-preloader.rb:112:in `eval'
  /usr/share/passenger/helper-scripts/rack-preloader.rb:112:in `preload_app'
  /usr/share/passenger/helper-scripts/rack-preloader.rb:158:in `<module:App>'
  /usr/share/passenger/helper-scripts/rack-preloader.rb:29:in `<module:PhusionPassenger>'
  /usr/share/passenger/helper-scripts/rack-preloader.rb:28:in `<main>'