title: Devise: Suddenly cannot log in anymore
body: <p>I'm using Devise 1.3.4 for authentication for the backend in my app.
  For a couple of days now I cannot log in anymore.
  What happens is:</p>
  
  <ul>
  <li>I go to the login page /admin/sign_in</li>
  <li>Log in with good credentials</li>
  <li>See in the log that the login worked (last_sign_in_at, current_sign_in_at and current_sign_in_ip are set, sign_in_count is increased)</li>
  <li>Devise sessions controller tries to forward me to the after_sign_in_path_for I specified in my application controller (Admin::DashboardsController#show)</li>
  <li>Then suddenly the sign in page is rendered again. No redirect, no nothing.</li>
  </ul>
  
  <p>I checked the before_filters and it definitely is Devise's autorize_admin_user! filter that causes the problems (filters before it are called, filters after it are not called). Meaning that even after logging in successfully it doesn't recognize me as logged in.</p>
  
  <p>I realize that it is hard to come up with a solution without seeing most of my code.
  So my first question would be:</p>
  
  <p>How can I debug this error?
  How can I retrace where exactly the login doesn't work? Do I have to dig in to Warden?
  Can it be a session/cookie problem? How could I debug that?</p>
  
  <p>All ideas appreciated!</p>
  
  <p>This is what the log says:</p>
  
  <pre><code>Started GET "/admin/sign_in" for 127.0.0.1 at 2011-05-20 13:49:11 +0200
  [Barista] Compiling all scripts for barista
  [Barista] Compiling all coffeescripts
    Processing by Admin::SessionsController#new as HTML
  Rendered admin/shared/_header.html.haml (3.1ms)
  Rendered admin/shared/_menu.html.haml (1.7ms)
  Rendered admin/sessions/new.html.haml within layouts/admin (128.7ms)
  Completed 200 OK in 171ms (Views: 133.0ms | ActiveRecord: 0.0ms)
  
  
  Started POST "/admin/sign_in" for 127.0.0.1 at 2011-05-20 13:49:15 +0200
  [Barista] Compiling all scripts for barista
  [Barista] Compiling all coffeescripts
    Processing by Admin::SessionsController#create as HTML
    Parameters: {"utf8"=&gt;"✓", "authenticity_token"=&gt;"VLjjo6W+sd7yRH3SRSNpUN3L8a+OaOgCUpJgB5VaGEM=", "admin_user"=&gt;{"email"=&gt;"my@email.com", "password"=&gt;"[FILTERED]", "remember_me"=&gt;"0"}, "commit"=&gt;"Sign in"}
    AdminUser Load (0.7ms)  SELECT `admin_users`.* FROM `admin_users` WHERE `admin_users`.`email` = 'admin3@gmail.com' LIMIT 1
    SQL (0.2ms)  BEGIN
    AREL (0.3ms)  UPDATE `admin_users` SET `last_sign_in_at` = '2011-05-20 11:49:15', `current_sign_in_at` = '2011-05-20 11:49:15', `current_sign_in_ip` = '127.0.0.1', `sign_in_count` = 3, `updated_at` = '2011-05-20 11:49:15' WHERE `admin_users`.`id` = 33
    SQL (0.5ms)  COMMIT
  Redirected to http://myapp.dev/admin
  Completed 302 Found in 160ms
  
  
  Started GET "/admin" for 127.0.0.1 at 2011-05-20 13:49:15 +0200
  [Barista] Compiling all scripts for barista
  [Barista] Compiling all coffeescripts
    Processing by Admin::DashboardsController#show as HTML
  Completed   in 26ms
  
  
  Started GET "/admin/sign_in" for 127.0.0.1 at 2011-05-20 13:49:16 +0200
  [Barista] Compiling all scripts for barista
  [Barista] Compiling all coffeescripts
    Processing by Admin::SessionsController#new as HTML
  Rendered admin/shared/_header.html.haml (3.5ms)
  Rendered admin/shared/_menu.html.haml (2.0ms)
  Rendered admin/sessions/new.html.haml within layouts/admin (134.9ms)
  Completed 200 OK in 182ms (Views: 139.2ms | ActiveRecord: 0.0ms)
  </code></pre>