Rails / Devise / Omniauth combo says email is nil but it's not - ruby-on-rails

Question

I was setting up Devise & Omniauth as per railscasts like I usually do, only now I'm using Rails 5.0.1 and ruby 2.3.3
When I go to add a user, not even using Omniauth, just using a basic email + password + confirmation the page reloads with an error of "Email can't be blank". I can see the parameters include the email.
I used Pry to investigate - things get weird here.
[1] pry(#<RegistrationsController>)> params
=> <ActionController::Parameters {"utf8"=>"✓", "authenticity_token"=>"[removed this!]", "user"=><ActionController::Parameters {"email"=>"test#test.com", "password"=>"testtest", "password_confirmation"=>"testtest"} permitted: false>, "commit"=>"Sign up", "controller"=>"registrations", "action"=>"create"} permitted: false>
[3] pry(#<RegistrationsController>)> #user
=> #<User id: nil, email: "test#test.com", created_at: nil, updated_at: nil, first_name: nil, last_name: nil, image_url: nil, headline: nil, dob: nil, gender: nil, webpage_url: nil, twitter: nil, linkedin: nil, blog_url: nil, description: nil, country: nil, state: nil, city: nil, phone: nil, full_bio: nil, profile_claimed: nil>
[4] pry(#<RegistrationsController>)> #user.class
=> User(id: integer, email: string, encrypted_password: string, reset_password_token: string, reset_password_sent_at: datetime, remember_created_at: datetime, sign_in_count: integer, current_sign_in_at: datetime, last_sign_in_at: datetime, current_sign_in_ip: string, last_sign_in_ip: string, created_at: datetime, updated_at: datetime, first_name: string, last_name: string, image_url: string, headline: string, dob: date, gender: string, webpage_url: string, twitter: string, linkedin: string, blog_url: string, description: text, country: string, state: string, city: string, phone: string, full_bio: text, type: string, profile_claimed: boolean)
[5] pry(#<RegistrationsController>)> #user.email
=> nil
[7] pry(#<RegistrationsController>)> #user.errors
=> #<ActiveModel::Errors:0x007f9de2c82da0
#base=
#<User id: nil, email: "test#test.com", created_at: nil, updated_at: nil, first_name: nil, last_name: nil, image_url: nil, headline: nil, dob: nil, gender: nil, webpage_url: nil, twitter: nil, linkedin: nil, blog_url: nil, description: nil, country: nil, state: nil, city: nil, phone: nil, full_bio: nil, profile_claimed: nil>,
#details={:email=>[{:error=>:blank}, {:error=>:blank}]},
#messages={:email=>["can't be blank"], :password=>[], :password_confirmation=>[]}>
[8] pry(#<RegistrationsController>)> #user.email.class
=> NilClass
You can see that if I access #user it returns the hash containing the email. However if I try #user.email I get nil. And when I ask for #user.errors the message says email can't be blank.
I've been hunting a while on this one. Thanks in advance for any help!
--
class ApplicationController < ActionController::Base
before_action :configure_permitted_parameters, if: :devise_controller?
protected
def configure_permitted_parameters
devise_parameter_sanitizer.permit(:sign_up, keys: [:email])
end
end
Puma server.
Started POST "/users" for ::1 at 2017-01-07 20:42:57 -0500
Processing by RegistrationsController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"tfBeZtXEFdZV9Rx3dJgCQJ+9hHuvgFcbc3dD9D7Q6yKki4GmlVw17/qlDm2squ3hKngX3Juu12iaM1Dki9qXig==", "user"=>{"email"=>"test#test.com", "password"=>"[FILTERED]", "password_confirmation"=>"[FILTERED]"}, "commit"=>"Sign up"}
(0.1ms) begin transaction
(0.1ms) rollback transaction
Rendering registrations/new.html.erb within layouts/application
Rendered devise/shared/_links.html.erb (0.7ms)
Rendered registrations/new.html.erb within layouts/application (4.6ms)
--
rails console
Running via Spring preloader in process 12578
Loading development environment (Rails 5.0.1)
2.3.3 :001 > u = User.new
=> #<User id: nil, email: "", created_at: nil, updated_at: nil, first_name: nil, last_name: nil, image_url: nil, headline: nil, dob: nil, gender: nil, webpage_url: nil, twitter: nil, linkedin: nil, blog_url: nil, description: nil, country: nil, state: nil, city: nil, phone: nil, full_bio: nil, profile_claimed: nil>
2.3.3 :002 > u.email = "test#test.com"
=> "test#test.com"
2.3.3 :003 > u.password = "password"
=> "password"
2.3.3 :004 > u.password_confirmation = "password"
=> "password"
2.3.3 :005 > u.save
(0.2ms) begin transaction
(0.1ms) rollback transaction
=> false
2.3.3 :006 > u.errors
=> #<ActiveModel::Errors:0x007f87163eeac8 #base=#<User id: nil, email: "test#test.com", created_at: nil, updated_at: nil, first_name: nil, last_name: nil, image_url: nil, headline: nil, dob: nil, gender: nil, webpage_url: nil, twitter: nil, linkedin: nil, blog_url: nil, description: nil, country: nil, state: nil, city: nil, phone: nil, full_bio: nil, profile_claimed: nil>, #messages={:email=>["can't be blank"]}, #details={:email=>[{:error=>:blank}, {:error=>:blank}]}>

Answer 1

I believe permitted: false says that your parameters are not permitted and can't be saved. Did you set up strong parameters for Users controller?