PayPal Standard Donations Error

Hello,

Our website seems to be having an issue with accepting PayPal standard donations. When families try using paypal to make a donation, they get the following error message:

“There has been a critical error on this website.

Learn more about debugging in WordPress.”

We have been using this form/system to accept donations for a few years, and it was working fine just last month. Not sure if something is wrong on our end or if it’s a PayPal issue, so any information/tips are greatly appreciated. We have disabled PayPal for the time being and are asking people to make offline donations to avoid the mess.

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