@kor3k every form has a configured submit method. Check is there because there's no point in executing rest of the code if the request method doesn't match the form's method. If methods don't match, request shouldn't be handled.

To solve your issue you could create a form for the current request method, unless it's a GET:

$method = $request->isMethod('GET') ? 'POST' : $request->getMethod();
$form = $this->createForm(new TaskType(), $task, array('method' => $method));

Closing as this is not a bug.

it is not really a bug, however it effectively prevents users from setting the method in the template AND using the RequestHandler at the same time.

i have created a PR #9178 for making RequestHandler a service, so current behavior remains, but is overrideable.

btw the solution you propose is not satisfactory.

i am yielding the form in >1 controller actions. but the form creation process has some additional logic than just Controller::createForm call, like conditional data injecting, conditional options setting etc. so i have this whole form creation process in a getForm method.

so, if i would like to set the method in the controller, then i'd have to duplicate the getForm code in every action which yields the form, because the Form does not allow method changing after it has been built. and this would violate DRY.

Why don't you create 2 forms one for "new" with POST method and then one for edit where you "extend" the "new" one. And set the PUT method in builder for the other one.

@kor3k if you're doing some additional actions than it's effectively not a single form. You just put part of the logic into the controller while it should be in the form - you could use events for this. As @mvrhov suggested in some cases it might be worth creating multiple form types.