bundler - rails app not starting, 'ActiveSupport::Deprection' error on assets:precompile -

my (previously working) app of sudden wont start on aws elastic beanstalk , i'm getting strange error 'activesupport::deprection', looks mis-spelling of deprecation?

this seems rails 4.2.3 (released few weeks ago). changing rails = 4.2.2 in gemfile has fixed issue now. post better answer when figure out what's happened