If you're seeing this error, the cause may be one of the two explained in the error screen itself:
- You are testing your site by opening it in a browser as a static HTML file in your computer's filesystem. In this case its URL will not start with
https://. This will not work, because browsers don't treat these pages as normal web resources and thus they do not automatically send the "Referer" header when you submit a form. Formspree requires that header to work. This can be solved if you just open your HTML files as a web resource from a local web server. If you're on Mac or Linux, just type python -m SimpleHTTPServer 8000 or your HTML files directory and visit http://localhost:8000 on your browser. If you're on Windows, try installing one of the following super simple web servers: Web server for Chrome, thttpd or Quickshare.
- You are using an old Safari version, Safari mobile or some other browser that is not recent Chrome, Firefox or Edge. In this case you could have been a victim of an old HSTS policy we had on Formspree that didn't allow sites to post content to non-https versions of Formspree. In this case please change your form's