Getting JS error:

Uncaught TypeError: Object [object Object] has no method 'pluploadQueue'

And no widget rendered, just field description and title.

<?php
$form
['my_element'] = array(
 
'#type' => 'plupload',
 
'#title' => t('Upload files'),
 
'#description' => t('This multi-upload widget uses Plupload library.'),
 
'#upload_validators' => array(
   
'file_validate_extensions' => array('jpg jpeg gif png txt doc xls pdf ppt pps odt ods odp'),
   
'my_custom_file_validator' => array('some validation criteria'),
  ),
);
?>

Comments

Do you have Plupload library installed?

I'm getting this if I use jQuery Update, choose 1.8 and choose minified sources or a CDN. Strangely enough, unminified sources work fine. Could be the order that scripts get loaded. You may want to move this issue to that project.

For now we've disabled minification in the jQuery Update configuration, and Plupload renders and behaves correctly. If I get a chance to return to this, I'll see if I can figure out more.

Might actually be more to it than that. Just Plupload+Jquery Update don't seem to reliably reproduce.