Rails: Passenger debug

if show error message , you check ↓

$ tail error_log
-------
[ 2015-02-07 23:43:10.2449 1276/7f1a10a6b700 Pool2/Implementation.cpp:287 ]: Could not spawn process for application /var
/: An error occured while starting up the preloader.
  Error ID: 9a4609eb
  Error details saved to: /tmp/passenger-error-mWzkyA.html
-------
$ view passenger-error-mWzkyA.html

in `method_missing'
  /app/models/user.rb:4:in `<class:User>'
  /app/models/user.rb:1:in `<top (required)>'  ← code check !