"Inheritance security rules violated" when converting web app and controls to 4.0

When converting an ASP.NET Web application and / or Custom Controls to .NET Framework 4, you may get a security rules violation about inheritance.

There have been some security enhancements in .NET 4.0 around Security Transparency.

You can read about them here: http://msdn.microsoft.com/en-us/library/dd233102%28VS.100%29.aspx


You can try setting the following assembly level attribute to force .NET 2.0 security rules.

[assembly: System.Security.SecurityRules(System.Security.SecurityRuleSet.Level1)]

this directive would be placed in the AssemblyInfo.cs file under the Properties folder of your application.