Invalid form authentication ticket after framework4.0 upgrade

I haven't been there for a long time, and I almost forgot my password. By the way, I recorded the small problems encountered in today's configuration environment.

The form authentication used by the website is used for SSO login, And the framework20 configuration environment used by the domain name is logged on.

After a topic is upgraded to the 4.0 environment, the authentication ticket becomes invalid. The log information is as follows:

Event code: 4005
Event message: Forms authentication failed for the request. Reason: the ticket supplied was invalid.

The solution is as follows:

Or the machinekey problem. In the Microsoft. NET \ framework directory, find the 4.0 configuration directory v4.0.30319 \ config and change the machinekey of machine. config to the 2.0 configuration file with the same machinekey.

Or directly add the machinekey to the Web. config of the 4.0 website.

Invalid form authentication ticket after framework4.0 upgrade