Form with manged_file filed is not submitted? I have a form in my drupal module. in my form, I have used manged_file field.
form name is "difference_form" and I have created two functions.
one is "function diffence_form" for form definitions.
here is code:

function difference_form() {
  $validators = [];
  $form['new_image'] = [
    '#type' =&gt; 'managed_file',
    '#name' =&gt; 'new_personal_image',
    '#title' =&gt; 'New Image',
    '#description' =&gt; theme('file_upload_help', [
      'description' =&gt; 'Please insert your new image.',
      'upload_validators' =&gt; $validators,
    ]),
    '#upload_location' =&gt; $path,
    '#default_value' =&gt; variable_get('new_image', ''),
    '#upload_validators' =&gt; $validators,
  ];

  $form['submit'] = [
    '#type' =&gt; 'submit',
    '#value' =&gt; 'submit',
  ];

  return $form;
}

function difference_form_submit($form, &amp;$form_state) {
  drupal_set_message('test_form_submit called');
}


and also I have created a block for this form in hook_block_view.

function customize_block_view($delta = '') {

  $block = NULL;
  $block['content'] = drupal_get_form('difference_form');
  $block['subject'] = 'Difference Form';
  return $block;
}


Form is rendered correctly, but when I click on submit button, submit function is not called.

I tried to debug my codes. I found if I remove file_managed field from form definition, submit function works.

also if I found if I renamed all difference_form to another name for example "test_form"

drupal_get_form('test_form');
function test_form(){....}
and
function test_form_submit(......

submit function works.
it seems system is sensitive on "difference_form" only

I am thinking might the expression "difference_form" be blocked in database or somewhere else ?
I found the reason of this problem finally.
It was as a result of jQuery code mistakes.

in form submission, I tried to disable submit button immediately after clicking.
I had to change the coding because set button disable causes this problem.