500 Error on Signup Form

Hi there,

I would greatly appreciate your help in resolving something that went wrong this past weekend. We changed our theme from Divi to Stack. Somewhere along the line our Participant’s Database Signup Form has broken.

I have the shortcode placed on the page here https://bhrscholarsassociation.org/become-a-member-2/, a duplicate page I made for testing. Right now the form is displaying correctly, but when I fill out the fields and click “submit” I get a 500 Internal Server Error. It is not sending the email with the information, either.

I’ve tried a few things on my own, including making a backup of the site and going through deleting/deactivating other plugins, tried deleting and reinstalling the plugin, too. The re-install didn’t help, the form reverted to the default form which also returned a 500 error. I reverted the site to the backup since nothing worked. I’m obviously not a developer, or particularly savvy at this sort of thing, and have no idea what else to try.

Thanks so much for your help!

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