I was following the article How to: Implement Role Based Access Control (RBAC) in a Claims-Aware ASP.NET Application Using WIF and ACS and was getting below error on page load event of my ASP.net application,
Two important things to remember are
1. The article doesn’t tell you configure trust between your ASP.net relying part application and ACS so you should go ahead and do that via “Add STS reference” in Visual Studio 2010 or “Identity and Access” in Visual Studio 2012 .
2. The article tells you to set “user” in lower case in the output claims value in ACS management portal but later uses “User” as role name in the code. So it turns out that the role name is case sensitive. You should ensure that the role name specified in the output claims value in ACS management portal and the one you are using in code should match case wise.
I fixed my code to use “user” and it resolved the issue for me.