HTTP ERROR 500

Ever since the last update to Contact Form 7 I have been unable to use the Butterfly Report Form (coded in HTML with an internal HTML form) that is supposed to go to a php page (https://howardbirds.website/butterflyreport/ButterflyReport_acknowledge.php) that processes the request, composes a response to the sender, and sends formatted data to me and other uses who require it. But since the update, everyone is getting the following error message:

This page isn’t working right now
howardbirds.website can’t currently handle this request.
HTTP ERROR 500

• This topic was modified 7 months, 2 weeks ago by hcbcwebster.
• This topic was modified 7 months, 2 weeks ago by hcbcwebster.

The page I need help with: [log in to see the link]