Undefined index: form_build_id in ajax_get_form()

Can you post exact steps to reproduce?

If you wrote any custom code, can you provide that as well?

I am also getting this problem.
I am very surprised that it is unresolved! Either very few people are usuing ajax with tableselect (seems unlikely?)
or there is some workaround that I just haven't run across yet.
Below is an example which uses ajax and tableselect to reproduce the white screen of death problem I get.
The example is contrived and somewhat patched together but it reproduces the problem exactly it seems.
If you have the form recreated by typing something in the textfield and hitting enter and then click "next" you will get the white screen of death. If you click back Drupal informs you of the error
Notice: Undefined index: form_build_id in ajax_get_form() (line 320 of /var/www/html/includes/ajax.inc).
I notice that clicking "next" the URL changes to something which is clearly not right:
?q=system/ajax&page=1

Below is the module code. If there is some workaround to getting ajax and tableselect to work well together I would appreciate knowing what it is! This seems to me to be a fairly serious bug!

function temp_module_menu() {
    $items['temp_module'] = array(
        'title' => 'Drupal 7 test pager',
        'type' => MENU_CALLBACK,
        'page callback' => 'temp_module_test_pager',
        'access callback' => TRUE,
    );
    return $items;
}

function temp_module_test_pager() {
    return drupal_get_form('temp_form');
}

function list_refresh($form, &$form_state) {
    return $form;
}

function temp_form($form, &$form_state) {
    $form['#prefix'] = '<div id="search_list">';
    $form['#suffix'] = '</div>';

    $form['title'] = array(
        '#type' => 'textfield',
        '#title' => t('Course Title'),
        '#size' => 30,
        '#maxlength' => 30,
        '#required' => FALSE,
        '#prefix' => '<td>',
        '#suffix' => '</td></tr>',
        '#ajax' => array(
            'callback' => 'list_refresh',
            'wrapper' => 'search_list',
            'keypress' => TRUE,
            'method' => 'replace',
            'effect' => 'fade'
        ),
    );
//Create a list of headers for your Html table (see Drupal 7 docs for theme_table here
    $header = array(
        'nid' => t('title'),
        'title' => t('nid'),
        'type' => t('type'),
        'created' => t('created'),
        'status' => t('status'),
    );

//Create the Sql query. This uses various parts of Drupal 7's new DBTNG database abstraction layer.

    $query = db_select('node', 'n')
            ->condition('status', 1) //Only published nodes, change condition as it suits you
            ->extend('PagerDefault')  //Pager Extender
            ->limit(2)    //2 results per page
            ->extend('TableSort')  //Sorting Extender
            ->orderByHeader($header)//Field to sort on is picked from $header
            ->fields('n', array(
        'nid',
        'title',
        'type',
        'created',
        'status',
            ));

    $results = $query
            ->execute();

    $rows = array();
    foreach ($results as $node) {
        $rows[$node->nid] = array(
            'title' => l($node->title, 'node/' . $node->nid),
            'nid' => $node->nid,
            'type' => $node->type,
            'created' => format_date($node->created),
            'status' => $node->status
        );
    }
    $form['registration_table'] = array(
        '#type' => 'tableselect',
        '#header' => $header,
        '#options' => $rows,
        '#js_select' => FALSE,
        '#multiple' => TRUE,
        '#prefix' => '<table><tr><td>',
        '#suffix' => '</td></tr>',
    );
    $form['submit'] = array('#type' => 'submit',
        '#value' => t('Register'),
        '#disabled' => FALSE,
        '#prefix' => '<tr><td>',
        '#suffix' => '</td></tr></table>');
    $form['pager'] = array('#markup' => theme('pager'));
    return $form;
}

Fixing tags

Is there any alternative or workaround (or even a tentative D7 patch?) that can be used while waiting for the backport?
I would like this functionality for a current project and this is an unforeseen bottleneck!

So what was the solution?

I added these extra fields in my template (they seemed logical). Everything works for me:

print drupal_render($form['form_build_id']);
print drupal_render($form['form_token']);
print drupal_render($form['form_id']);
print drupal_render($form['webform_ajax_wrapper_id']);

(ps)

Ran into this today because I forgot:

<?php print drupal_render_children($form); ?>

Woops :).

I'm using Drupal 7 and have the same problem, but I don't understand where to put the 4 drupal_render commands. I don't have any templete file, just include files. The relevant code follows:

class xxxEntityUIController extends EntityDefaultUIController {
...
  public function hook_menu() {
    $items = parent::hook_menu();
    .....
    $items['player/%entity_object/gamelog'] = array(
      'load arguments' => array(0, 1),
      'title' => t('Game Log'),
      'access arguments' => array('view basket entities'),
      'page callback' => 'drupal_get_form',
      'page arguments' => array('player_gamelog_form', 0, 1),
      'type' => MENU_LOCAL_TASK,
      'context' => MENU_CONTEXT_PAGE | MENU_CONTEXT_INLINE,
      'weight' => -40,
    );
    .....
    return $items;
  }

  public function hook_forms() {
    $forms = parent::hook_forms();
    $forms['player_gamelog_form'] = array('callback' => 'player_gamelog_form');
    ....
    return $forms;
  }
}

function player_gamelog_form($form, &$form_state, $entity_type = 'player', $entity = NULL) {
  drupal_set_title (is_null($entity) ? 'Unknown' : $entity->defaultLabel());
  $values = key_exists('values', $form_state) ? $form_state['values'] : array();
  $form['filters'] = array(
    '#type' => 'container',
    '#attributes' => array('class' => array('container-inline')),
  );
  $form['filters']['season'] = array(
    '#type' => 'select',
    '#title' => t('Season'),
    '#options' => ..... ,
    '#ajax' => array(
      'callback' => 'basketentities_param_form_callback',
      '#path' => array('log_table'),
      'wrapper' => 'log_table',
      'method' => 'replace',
      'effect' => 'fade',
    ),
  );

  $header = array(
    'Game',
    array ('data' => 'Season', 'field' => 'season', 'sort' => 'DESC'),
    array ('data' => 'Day', 'field' => 'day', 'sort' => 'DESC'),
   ......
    array ('data' => 'PF', 'field' => 'pf'),
  );
  $sq = db_select('bs_stats_players', 'p')
    ->fields('p', array('game', 'season', 'day', ..... 'pf'))
    ->extend('TableSort')->orderByHeader($header)
    ->extend('PagerDefault')->limit(5);
  ....
  if(key_exists('season', $values) && (int)$values['season'] !== 0)
    $sq->condition('season', (int)$values['season']);

  $form['log_table'] = array(
    '#theme' => 'table',
    '#header' => $header,
    '#rows' => array(),
    '#empty' => t('No games.'),
    '#prefix' => '<div id="log_table">',
    '#suffix' => '</div>',
  );
  foreach($sq->execute() as $row) {
    $game = ....
    $link = ....
    $form['log_table']['#rows'][] = array(
       ....
    );
  }
  $form['log_pager'] = array('#theme' => 'pager');


  return $form;
}

I would be grateful if you could point me to the right direction, since I'm quite new to Drupal development.

I've posted a workaround for this issue here for anyone who is struggling with this.

Work fine with #12.

Why not create a method for system required form field like drupal_render_form_header($ajax = FALSE); ?

There were never really any steps to reproduce here and it only seemed to be affecting custom code, so I'm going to close this.

If anyone still has the issue in D7 or D8 please open a new ticket with clear steps to reproduce, starting with 'Install Drupal'. If your issue only occurs with custom code, then it's probably a support request rather than a bug.