Devise Omniauth报错：Users::OmniauthCallbacksController找不到github方法

Let’s walk through the most likely issues that could be causing this error, even though you’ve already checked a lot of boxes:

1. Double-check your controller file path and naming #

Rails relies heavily on convention, so your controller file must be at:
app/controllers/users/omniauth_callbacks_controller.rb
Make sure the users/ folder exists inside controllers/, and the filename is all lowercase with underscores (no camelCase or typos like omniauth_callback_controller.rb missing an "s").

2. Verify your controller class structure #

Looking at your code snippet, ensure the github method is inside the controller class with proper indentation. A common mistake is accidentally placing the method outside the class definition, which means Rails won’t recognize it as part of the controller. Your controller should look like this:

class Users::OmniauthCallbacksController < Devise::OmniauthCallbacksController
  def github
    @user = User.from_omniauth(request.env["omniauth.auth"])
    if @user.persisted?
      sign_in_and_redirect @user, event: :authentication
      set_flash_message(:notice, :success, kind: "Github") if is_navigational_format?
    else
      redirect_to root_path
    end
  end
end

No missing end keywords, and the def github is properly nested under the class.

3. Restart your Rails server! #

This is such a simple step but easy to overlook. Any changes to routes, controllers, or Devise initializers require a server restart to take effect. If you’ve been modifying code without restarting, the server is still running old code that doesn’t include your github method.

4. Confirm your route mapping #

Run rails routes (or rake routes for older Rails versions) and look for the GitHub callback route. It should look like this:

user_github_omniauth_callback GET|POST /users/auth/github/callback(.:format) users/omniauth_callbacks#github

Double-check that the action is indeed github and the controller is users/omniauth_callbacks. If it’s pointing to a different action or controller, your devise_for route configuration might have a typo.

5. Check for syntax errors in related files #

Even though the error points to the controller, a syntax error in your User model or Devise initializer could break the loading of related code. For example:

• In your User model’s from_omniauth method, ensure all end keywords are present and properly nested. Also, first_or_create automatically saves the user, so you don’t need user.save! (this won’t cause the action-not-found error, but it’s a good cleanup).
• Make sure your Devise initializer’s config.omniauth :github line is inside the Devise.setup do |config| block, with no typos in the provider name (:github, not :Github or :gitHub).

6. Rule out route conflicts #

Check if any other routes in your routes.rb are defined before the devise_for :users line. A wildcard route or a similarly named route might be overriding the Omniauth callback route, preventing Rails from reaching your controller. Always place devise_for before custom routes to avoid this.

Start with the first three points—they’re the most common culprits for this exact error. If none of these work, try creating a minimal test case (a fresh Rails app with just Devise and Omniauth-GitHub) to see if the issue is specific to your app’s configuration.

内容的提问来源于stack exchange，提问作者Alli T