Rails: "BCrypt::Errors::InvalidHash" when trying to sign in

I am trying to finish a project. I am working with user models. When I signup everything seems ok . But when I try to signin the same member I get this error.

We're sorry, but something went wrong. heroku logs file shows error as:

BCrypt::Errors::InvalidHash (invalid hash):
  app/controllers/sessions_controller.rb:8:in `create'

my sessions_controller is :

class SessionsController < ApplicationController

  def new
  end

   def create
    user = User.find_by_email(params[:session][:email])
    if user && user.authenticate(params[:session][:password])
      sign_in user
      redirect_to user
    else
      flash.now[:error] = 'Invalid email/password combination'
      render 'new'
    end
  end
  
  
  def destroy
    sign_out
    redirect_to root_path
  end
end

and user model is :

class User < ActiveRecord::Base
  attr_accessible :email, :name, :nickname,:password, :password_confirmation 
  has_secure_password
 
  
  before_save { |user| user.email = email.downcase }
  before_save { |user| user.nickname = nickname.downcase }
  before_save :create_remember_token
....validations......

	private

    def create_remember_token
      self.remember_token = SecureRandom.urlsafe_base64
    end
end 

this is my session.helper

module SessionsHelper

  def sign_in(user)
    cookies.permanent[:remember_token] = user.remember_token
    self.current_user = user
  end
  def signed_in?
    !current_user.nil?
  end

  def current_user=(user)
    @current_user = user
  end
  
  def current_user
    @current_user ||= User.find_by_remember_token(cookies[:remember_token])
  end

  def sign_out
    self.current_user = nil
    cookies.delete(:remember_token)
  end
end

I tried heroku rake db:migrate, heroku restart.. there is no change.

This means that the hash stored in password_digest is not a valid BCrypt hash (including if the field is empty).

Based on the comments, it looks like you just created the user at a time the has_secure_password wasn't there, so the password digest never got stored. Look in the database, you'll probably see that password_digest is empty for that user. Remove the user from the database and re-create with your new working code and it should work.

While discussing with in the comments though, I made an (incorrect) guess about why the passwords would be wrong, and I already wrote up the explanation. So here it is for any future visitor that does have this problem, even though it doesn't apply directly here:

---

This typically happens when you switch from using SHA1 or another algorithm to BCrypt but fail to re-hash the passwords in BCrypt. Since you don't have access to the original passwords (or at least you shouldn't...), it's a bit ugly to switch because you have to use both BCrypt and the original authentication scheme. For example, if you were using SHA1 before and now use BCrypt, you have to treat the SHA1 password hash as the plain text password for BCrypt input. For example, you might create a BCrypt digest like this:

sha1_password = Digest::SHA1.hexdigest("#{salt}#{real_password}")
self.password_digest = BCrypt::Password.create(sha1_password).to_s

Then, you can create bcrypt password_digests based on the sha1 password hashes that you do have access to.

You would authenticate like this:

sha1_password = Digest::SHA1.hexdigest("#{salt}#{attempted_password}")
BCrypt::Password.new(self.password_digest) == sha1_password

I used SHA1 in the above examples, but this will work for other hashing algorithms as well.

An update to the BCrypt gem fixed this issue for me

I already had live users, and likewise already saved unencrypted passwords into the database. Once I started using bcrypt, it was expecting an encrypted password, and when it didn't find it, it produced this error.

Therefore, I added this rescue to catch the error and prompt the legacy users to reset their password:

begin
	# your code that attempts to login the user
rescue BCrypt::Errors::InvalidHash
  flash[:error] = 'We recently adjusted the way our passwords are stored. Please click the "forgot username or password?" link to re-establish your password. Thank you for your understanding!'
  redirect_to password_resets_url
end 

Hope this helps.