On my website, any trailing slash is resulting in an error. How do I fix this?
What do you have going on with your site? If different pages have different headers, and the Contact page is a different theme. It allows the trailing slash/: http://liberaltech.net/pseudoscience/contact/
Looking at the page source I notice that you have a favicon before the document declaration. Try turning off plugins one by one to see if it fixes your issue.
Here are 2 of the few different headers viewed in source: