What is the use of <%@ page aspcompat=true %> attribute ?
This attribute works as a compatibility option. We know that ASP worked in STA model and ASP.NET works in MTA model, but what if your ASP.NET application is using a VB COM component. In order that VB COM runs properly in ASP.NET threading model we have to fix attribute. After defining the ASPCOMPAT directive attribute ASP.NET pages runs in STA model & hence building the compatibility between the ASP.NET and old COM components that does not support the MTA model.