Hi,Yes you will have to convert all the documents to JPG in order to submitthe form.

Hi,  My account has been terminated by Shopify saying that I've violated one of the policy with no further explanation. I've tried to submit the dispute form however got Application Error. I contacted the Shopify Support but they couldn't help much. ...

How did you go? I've converted all my files to png but still got the Application Error message

Happened to me last night as well. Received an email from Shopify saying that I've violated the policy hence my account has been disabled. No further explanation and when I submitted the dispute form. I got the same message