Odtnhj

1) There is this Controller Function I made:

 /**
 * @Route("/add", name="add" )
 */
public function add_question()

 return $this->render("add.html.twig",);

2) When I go to http://127.0.0.1:8000/add Symfony returns this error:

The controller must return a response (null given). Did you forget to add a 
 return statement somewhere in your controller?

3) I have bunch of other Controllers that have the same structure and work correctly.

4) Whenever I want to add a new Controller, this error is being thrown.

5) I tried to return Response object - it doesn't work either.

EDIT:
my config/routes/annotations.yaml file:

controllers:
resource: ../../src/Controller/
type: annotation

Okay, I found the solution.

I have a few Controllers in my project.
One of them was located almost on top of the file and had following routing:

/**
* @Route("/question_id", name="questions" ) <--QUESTION ROUTE
*/

the logic of controller was like that:

function GenerateQuestionPage($question_id)

1find question in my database whose $id is equal to question_id.
2a. If you find such question then render proper twig template.
2b. If You don't find such question then you echo "No such question found";

Whenever I wanted to go to some page whose Routing was defined below the definition of the GenerateQuestionPage Controller, Symfony thought I was trying to use Question Route with
nonnumerical question_id. Then it was searching for such question in DB but obviously couldn't find so it wasn't returning Response object.

My solution was to relocate GenerateQuestionPage controller to the bottom of the file.