Error after submission

I have created a new form for my website.  While testing it out, I notice that after hitting submit I receive a message saying "Safari can't open the page "http://localhost/" because the page isn't valid.  What is this and why am I receiving it?

Hello,

I can't seem to find the Jotform on the page provided. Can you please direct us to the exact page where the form is embedded so we can check and investigate it here? Actually, it is my first time to hear such report so I believe it's not something to do with the form itself.

We'll await your reply. Thanks!