"Valid date is required for date_1" error while using drupal_form_submit() Field : field_date_1 
Type : Date 
Widget : Pop-up calendar
The settings for date field is as shown in 2 images




I get the values of a form_state into the $source_node and move that to $fs variable.The $source_node has date field stored as follows :  

 [field_pt_date_1] =&gt; Array
        (
            [und] =&gt; Array
        (
                    [0] =&gt; Array
                        (
                            [value] =&gt; 2010-08-27 00:00:00
                            [timezone] =&gt; America/Phoenix
                            [timezone_db] =&gt; America/Phoenix
                [date_type] =&gt; datetime
                        )
             )


)

 $fs['values']['field_date_1']['und'][0]['value'] = date('m/d/Y', strtotime($source_node-&gt;field_date_1['und'][0]['value']));
  $fs['values']['field_date_1']['und'][0]['timezone'] = $source_node-&gt;field_date_1['und'][0]['timezone'];
  $fs['values']['field_date_1']['und'][0]['timezone_db'] = $source_node-&gt;field_date_1['und'][0]['timezone_db'];
  $fs['values']['field_date_1']['und'][0]['date_type'] = $source_node-&gt;field_date_1['und'][0]['date_type'];


.........
The errors I am getting after executing the above code is as follows :

A valid date is required for date_1.

 drupal_form_submit('form_id', $fs, $source_node);
  $errors = form_get_errors();


And when checked the $errors variable I get 

$errors = Array
(
 [field_date_1][und][0][value] =&gt; A valid date is required for &lt;em class="placeholder"&gt;date_1&lt;/em&gt;.
)
I was facing similar kind of problem with drupal_form_submit.

After spending too much time following solution is working for me  

    $datetime = $source_node-&gt;field_date_1['und'][0]['value'] ;
    $form_state['values']['field_date_1']['und'][0]['value'] = array(
      'date' =&gt; date('d/m/Y', strtotime($datetime)),
      'time' =&gt; date('h:ia', strtotime($datetime)),
    );


Hope it will help someone