I keep receiving the 'this field is required' error at my drag & drop button even though I've attached a file.

I did not require any minimum quantity of uploads, and there is no minimum file size either.

I apologies for the inconvenience. We are trying to troubleshoot the issue. As it is the duplicate thread, of previous one.  So we will send you further updates on the original thread. That is on the below thread:

http://www.jotform.com/answers/889718-Multiple-File-Upload-Field-Error