Devise can be a daunting beast even if you've used it frequently. For new users, it can be especially baffling as the documentation often assumes a familiarity with its inner workings. To help bridge the gap, here are some frequent scenarios and possible solutions.
###Oh my God, it's complaining about unknown methods! What?!
This most commonly occurs because you have enabled features in your Devise model (e.g. user.rb) but didn't create the associated fields with a migration.
Devise's tendrils are manifold; each feature has an associated symbol in your model's devise
block, field(s) in your database, and configuration options in your Devise initializer.