Response.Redirect() to next page fails

Hello,

For some reason I have "GenericErrorPage.htm?aspxerrorpath=/" added to my URL link when it directs to the next page. The error happens when it directs a user from FORM1 to FORM3 with data populated from FORM2 to FORM1. I'm wondering what cause the URL change and how do I fix it?

Here is the Response.Redirect() to form3 

Response.Redirect("frmOrder3.aspx" + "?axa=" + strAXAId);

The URL string to FORM3 should be this URL below:
...