In multi-step forms, when i refresh the third step, it takes me to the first step

Hi. I read through so much to find what I'm doing wrong, but nothing found. This is just the problem I have. If I refresh on a multi-step form somewhere ... like in the 3rd step (will show example below), I get somewhere else.

I've made a demonstration test_module which does just show this effect. I'd be glad if someone pointed out, what the reason for the form's behavior is.

Here's the code. I'm sorry it's longer. It reflects the structure I want to achieve. Comments are there throughout the code. If it worked it could be a nice example how-to for multi-steps.

Problem description: Form works OK except for (F5) refreshes. You have the 'Main' form from where you can get to 'Primes' and 'Fibonacci'. OK until now. If you press 'Next' on those pages, you get to the next Prime or Fibonacci number. Refresh gets you to the first prime number from here on (from the second, third... Prime or Fibbonacci number). The form does handle well on the Main and the first Prime and Fib. number.

This can be made even simpler without the two branches. The problem stays. F5 (refresh) fires the submit handler with (to me) bad data.

//hook_menu to access this test at /test_page
function test_module_menu() {
  return array('test_page' => array(
    'title' => 'Multi-step test',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('_test_module_form'),
    'access callback' => TRUE,
  ));
}

//The form builder switches to sub-routines according to the content of $form_state['storage']['action']
//At the beginning the action is not defined and so the "default:" applies
function _test_module_form($form_state) {
  switch($form_state['storage']['action']) {
    case 'Primes':
      return _tmf_Primes($form_state);
    case 'Fibonacci':
      return _tmf_Fibonacci($form_state);
    default:
      return _tmf_Main($form_state);
  }
}

//The form submit switches just as the builder, nothing surprising here
function _test_module_form_submit($form, &$form_state) {
  switch($form_state['storage']['action']) {
    case 'Primes':
      _tmfs_Primes($form, $form_state);
      break;
    case 'Fibonacci':
      _tmfs_Fibonacci($form, $form_state);
      break;
    default:
      _tmfs_Main($form, $form_state);
      break;
  }
}

//The "default:" builder offers two buttons to navigate to the other two "sub-forms" below
function _tmf_Main($form_state) {
  $form['GoToPrimes'] = array(
    '#type' => 'submit',
    '#value' => 'Go to Primes',
  );
  $form['GoToFibonacci'] = array(
    '#type' => 'submit',
    '#value' => 'Go to Fibonacci',
  );
  return $form;
}

//This form is displayed when the ['action'] in storage was set to 'Primes' adn it just
//displays the first number from $form_state['storage']['Primes-DATA'] or a depleted message
//Two buttons - next and cancel (see submit handler)
function _tmf_Primes($form_state) {
  if (count($form_state['storage']['Primes-DATA'])) {
    $form['info'] = array(
      '#value' => '<p>Prime number is: '.reset($form_state['storage']['Primes-DATA']).'</p>',
    );
    $form['Next'] = array(
      '#type' => 'submit',
      '#value' => 'Next',
    );
  }
  else $form['info'] = array(
    '#value' => '<p>Prime numbers depleted</p>',
  );

  $form['Cancel'] = array(
    '#type' => 'submit',
    '#value' => 'Cancel',
  );
  return $form;
}

//Just the same for Fibonacci as for Primes in the previous
function _tmf_Fibonacci($form_state) {
  if (count($form_state['storage']['Fibonacci-DATA'])) {
    $form['info'] = array(
      '#value' => '<p>Fibonacci number is: '.reset($form_state['storage']['Fibonacci-DATA']).'</p>',
    );
    $form['Next'] = array(
      '#type' => 'submit',
      '#value' => 'Next',
    );
  }
  else $form['info'] = array(
    '#value' => '<p>Fibonacci numbers depleted</p>',
  );

  $form['Cancel'] = array(
    '#type' => 'submit',
    '#value' => 'Cancel',
  );
  return $form;
}

//The 'default:' submit handler sets the action according to the button clicked
//and prepares data
function _tmfs_Main($form, &$form_state) {
  switch($form_state['clicked_button']['#id']) {
    case 'edit-GoToPrimes':
      $form_state['storage']['action'] = 'Primes';
      $form_state['storage']['Primes-DATA'] = array(2,3,5,7,11,13,17,19,23);
      break;
    case 'edit-GoToFibonacci':
      $form_state['storage']['action'] = 'Fibonacci';
      $form_state['storage']['Fibonacci-DATA'] = array(1,2,3,5,8,13,21,34,55,89);
      break;
  }
}

//The submit handler for the Primes "sub-form". If next pressed, the data is shifted,
//Cancel clears ['storage'] and brings us thereby back to "default:" again
function _tmfs_Primes($form, &$form_state) {
  switch($form_state['clicked_button']['#id']) {
    case 'edit-Next':
      array_shift($form_state['storage']['Primes-DATA']);
      break;
    case 'edit-Cancel':
      unset($form_state['storage']);
      break;
  }
}

//same as above for Fibonacci
function _tmfs_Fibonacci($form, &$form_state) {
  switch($form_state['clicked_button']['#id']) {
    case 'edit-Next':
      array_shift($form_state['storage']['Fibonacci-DATA']);
      break;
    case 'edit-Cancel':
      unset($form_state['storage']);
      break;
  }
}

If this get's fixed, I'll make it a tutorial, I guess. Spent some time with it already...
Thanks for reading and for advice!

Just in case anyone is looking for a solution to this, ran into this problem with D7. Form some reason, the "form_build_id" was being changed after refresh in third step, so my solution was to store the "form_build_id" in storage after step 2, and restore it in step 3. My preliminary tests showed that after this, a refresh in step 3 retained values.

$form_state lose all its value after second step on page refresh.

If 'step' is the variable set in $form_state and user is on third step and refresh the page, form redirects to second step and losing 'step' value.

// 'step' is set in formSubmit
$form_state->set('step', 1);

// get 'step' in formBuild 
$form_state->get('step');

$form_state->isCached() returns TRUE on third step and is the reason of lost 'step' value.

There is various $form_state functions for Drupal 8 version

https://www.drupal.org/node/2310411

So I used this to disable that cache - $form_state->setCached(FALSE) before $form_state_setRebuild(). So it becomes

$form_state->setCached(FALSE);
$form_state->setRebuild();

I am facing some issue at D7 multistep form. After update PHP version 7.x to 8.x.
Please help me to provide some solution.

When I submit step 2 , it will not go to step2_form_submit . It always submit step1_form_submit.