Single Sign On with Forms Authentication

Question

I am trying to set up Single sign on for 2 websites that reside on the same domain

e.g.

http://mydomain (top level site that contains a forms-auth login page

Answer 1

There is a breaking change in ASP.NET 4.5's token generation

If you're mixing ASP.NET 4.5 apps with apps targeting earlier versions, you will need to ensure compatible tokens are used everywhere. Add this attribute to the on any site targeting .NET 4.5 or higher:

See this answer for more details. Special thanks to this comment which pointed me in the right direction.