You might be running into the issue mentioned here - https://rails.lighthouseapp.com/projects/8994/tickets/3144-undefined-method-for-string-ror-234
If so, there is a patch for it in the link 
Regards, Kashyap
how to? --
download the patch_file from the link I sent -
If you are on a unix like os - you need to navigate to (your gem installation path)/activesupport/lib/active_support and run patch -p1 < patch_file and provide the name message_verifier.rb
if on windows just google and find out how to apply the patch ... in the worst case, open the patch file and figure out the changes that need to be done in message_verifier.rb...
