Upgrading to ASP.NET 4.5/MVC 4 forms authentication fails

Question

I\'ve just downoaded a VS 2012 along with ASP.NET 4.5 and MVC 4.0 and was kicking the tires with a sample app and found that the forms authentication that works perfectly wi

Answer 1

If your forms authentication ticket needs to be shared between applications using an older version of the .NET framework, you must explicitly configure your .NET 4.5 apps to use the earlier machine compatibility modes, or they will not be able to encrypt/decrypt the forms authentication ticket.

In your .net 4.5 application's web.config, set the compatibility mode attribute:

This will allow your .NET 4.5 apps to work with forms authentication tickets generated by earlier .NET versions.

Note: If any of your servers do not have .NET Framework 2.0 SP2 installed, you will need to set the compatibility mode to "Framework20SP1" instead.

MSDN - MachineKeySection.CompatibilityMode Property