What did I do wrong with my iCal

I keep getting this message. I don't know what I did and I sure don't know how to fix it. I just had my hard drive replaced and my info migrated. It all used to work fine. Help!

https://calendar.google.com/calendar/dav/cordero.blanche@gmail.com/user///calendar.google.com/calendar/dav/cordero.blanche@gmail.com/user/ is not a location that supports this request.

what is this and how do I fix it?

thanks in advance

Blanche