Cache error on file upload with media, multiform, and plupload Checkout the log entries for a site I am working on, I found multiple pairs of the following notice/error:


  Error: Form build-id mismatch detected while attempting to store a
  form in the cache. Notice: Undefined index: #build_id in
  form_set_cache() (line 564 of /dir/includes/form.inc).


I am using media-2.x with plupload and multiform. The above messages are always logged for all files uploaded through plupload at file/add. Any ideas what is going on here and how to fix it? There will be a lot of file uploads on this site, and I really don't want the database filling up with these log entries.

I am getting these messages with Pantheon and with my local environment, so going to assume it is not a server configuration issue, Core and all modules are up to date. Php is 5.4.

Any help would be very much appreciated!
There is a bug in multiform that was introduced by recent changes to Drupal Core. The bug has been reported in the module's issue queue and a patch has been provided: https://drupal.org/node/2247527

The patch fixed the issue for me, and hopefully will be included in the next release of the module.