Here's the thing: if you fear #Tor so much that you want to block access from it, put up a message to its visitors stating that. Don't instead feign an error message or pretend that something with the connection went wrong, which can confuse the user into thinking your site is down ("Unable to connect", "The connection has timed out").

I'm tired of receiving "errors" like these lately only to use a webproxy like Anonymouse.org to quickly unmask the intention of the admin. I mean, what good does lying do in this case? Just fucking say it. Even a shitty #Cloudflare captcha is better than a misleading error message.