`superclass mismatch for class DashboardController` in development #8606

vfonic · 2024-12-12T19:45:03Z

vfonic
Dec 12, 2024

In new Rails 8 app, ActiveAdmin 4 (beta 15 or master), after raising an error such as NoMethodError in some AA resource class, triggers superclass mismatch for class DashboardController. The only mitigation is to restart the server.
The error needs to be raised at the "root" of the class/resource, such as:

ActiveAdmin.register Post do
  raise 'asd'
end

Here are the steps to repro:

rails new superclass_admin 
cd superclass_admin
bundle install
rails db:prepare
rails g scaffold post title:string
bundle add activeadmin --version "4.0.0.beta15"
rails g active_admin:install --skip-users
rails db:migrate
rails g active_admin:resource Post
rails s

After this, open app/admin/posts.rb and change permit_params :title to aaapermit_param :title.
You get undefined method 'aaapermit_params' for an instance of ActiveAdmin::ResourceDSL as expected.
Now change aaapermit_params back to permit_params and reload the page.

Expected behavior

The page should reload.

Actual behavior

superclass mismatch for class DashboardController

A quick patch that I discovered is to add this code to the gem:

# lib/active_admin/namespace.rb

    # TODO: replace `eval` with `Class.new`
    def register_resource_controller(config)
+     name_parts = config.controller_name.split('::')
+     const_name = name_parts.last
+     if Admin.const_defined?(const_name)
+       Admin.send(:remove_const, const_name)
+     end
      eval "class ::#{config.controller_name} < ActiveAdmin::ResourceController; end"
      config.controller.active_admin_config = config
    end

giuseb · 2024-12-17T21:26:06Z

giuseb
Dec 17, 2024

I have observed the same behavior

0 replies

aalyahya · 2024-12-27T17:13:35Z

aalyahya
Dec 27, 2024

I've experienced it as well

0 replies

vfonic · 2025-01-18T13:40:26Z

vfonic
Jan 18, 2025
Author

I've been seeing this happen many times in development. I believe it happens when there's a syntax error in the code (for example an extra end) so the code doesn't get reloaded correctly. This makes the code enter in "bad state". Even after fixing the syntax error, the issue persists. The admin doesn't load with superclass mismatch for class XXX. The only way to fix the issue is to restart the Rails server.

XXX is the alphabetically first resource. It could be DashboardController or it could be ArticleController if you have Article resource in your app.

@javierjulio I believe this is a bug and should be an issue rather than a discussion.

0 replies

sbounmy · 2025-06-30T13:25:43Z

sbounmy
Jun 30, 2025

Having the same issue here too

0 replies

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`superclass mismatch for class DashboardController` in development #8606

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superclass mismatch for class DashboardController in development #8606

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vfonic Dec 12, 2024

Expected behavior

Actual behavior

Replies: 4 comments

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giuseb Dec 17, 2024

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aalyahya Dec 27, 2024

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vfonic Jan 18, 2025 Author

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sbounmy Jun 30, 2025

`superclass mismatch for class DashboardController` in development #8606

vfonic
Dec 12, 2024

giuseb
Dec 17, 2024

aalyahya
Dec 27, 2024

vfonic
Jan 18, 2025
Author

sbounmy
Jun 30, 2025