```ruby
class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :null_session
  before_action :authenticate_user!

  add_flash_types :danger, :error, :success, :warning
end
```

Switch from Null Session to Exception for CSRF Protection
user
```ruby
class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :exception
  before_action :authenticate_user!

  add_flash_types :danger, :error, :success, :warning
end
```
assistant