Pet peeve – useless error messages

Here’s one from Github:

Clearly I have entered a URL in the text field. I assume what Github is trying to say is that this doesn’t adhere to whatever client side validation logic they’re using. Since I’m relatively tech savvy I can assume that maybe they want the http:// prefix. Sure enough that fixes the problem, but why could the error message not tell me that? Or even better, why not assume that if I don’t specify the scheme, it should use http or https?

In the words of Steve Krug, “Don’t make me think.”