I am using Drupal 7. I want to rebuild a part of form when a button is clicked. My form looks like this:

$form['me'] = array(
    '#type' => 'fieldset',
    '#value' => t('name'),
    '#prefix' => '<div id="me-wrapper>',
    '#suffix' => '</div>'

It contains various text fields and a submit button. The submit button looks like

$form['me']['save'] = array(
    '#type' => 'submit',
    '#validate' => array('save_validate'),
    '#submit' => array('save_submit'),
    '#ajax' => array(
        'wrapper' => 'me-wrapper',
        'callback' => 'me_ajax_callback'

in the save_submit function I set $form_state['rebuild] = true;

in ajax callback function

function me_ajax_callback($form, $form_state) {
    return $form['me'];

Now, what happens is first time when I click submit, the ajax returns data and replaces the wrapper. But, 2nd time when I do so, I get a POST Internal Server Error 500.

Looking around the Form API, I set $form_state['no_cache']=true; in submit handler and that prevents the POST error but still the AJAX response is empty.

It works fine if, I reload the page. So, in short, the first time I hit submit I get an AJAX response. On the second time, the response is blank.

  • What do your server logs say? An Internal Server Error 500 could mean anything. Aug 9, 2017 at 17:52
  • have you tried returning some text in the call back function? the value you should return have to be accessed via $form_state['values'] rather than the $form['me']? because you won't get what you need with $form, you have to use $form_state['values']['me'] why ? : because when you submit the '$form_state` holds your post values.
    – danuddara
    Aug 9, 2017 at 21:27

1 Answer 1


Ok, I have solved the issue and this might help someone in future. I was dealing with a form which was actually a collection of various small forms. Each small form had various text fields and submit handler. So, when reloading a small form using AJAX I was setting $form_state['rebuild'] = true, this in process rebuilt the whole form in the back. But AJAX callback only rendered a small part of form into the wrapper. So, when I pressed the button again there was post error as Drupal was expecting values in new rendered form whereas it got a mixture of Old and new form. It happens because Drupal while rendering a form into HTML adds id to it, e.g., id = edit-save but when we rebuild it without reloading the page, it changes to something like id = edit-save--2 and which keeps on to increment every time it's rebuilt. So, if your form needs rebuilding, reload the whole form else set $form_state['rebuild'] = false and that should allow subsequent AJAX calls without any post error.

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