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Assume that you have installed Microsoft .NET Framework 4.7. When you try to open Sitefinity based web applications, you may notice that they no longer work and throw an exception System.TypeInitializationException. Additionally, you may receive an error message that resembles the following:

The type initializer for 'Telerik.Sitefinity.Security.SecurityManager' threw an exception.


This problem occurs when there's a complex nested Sitefinity custom membership provider integration. This causes the applications to break and raise the exception. Until now, there have been issues that are related to Sitefinity based ASP.NET web applications only, and we are not aware of any other ASP.NET applications that face similar issues.


To fix this issue, install the Sitefinity hotfix and redeploy it:

Local site suddenly stopped working after running Windows 10 updates

Note We expect to release a fix for the .NET Framework 4.7 in future for this issue as well.

For more information about known issues in the .NET Framework 4.7, see Known issues in the .NET Framework 4.7.

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.

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