undefined method `deep_symbolize_keys' for

check you locale files if the parent locale is there.

for example in en.yml file, it may have en: as fist active text

undefined method `each' for false:FalseClass

if you get this type message and cant find the error location then there could be some reasons behind it.
This is one of them.

just review the locale files you have used, if it meets the yml syntax.
Or
take backup of original local files
create new rails app.
copy en.yml to yours application's locales dir.

if application runs then there must me errors in yml file. try to fix it.

cheers.