If you run your website on IIS7 you can run into the following HTTP errors: 500.22, 500.23
An ASP.NET setting has been detected that does not apply in Integrated managed pipeline mode.
If you don't want to change your web.config and still want to run the website on IIS7 you have to change the Application Pool of your Website.
Open IIS, go to your Application Pools, find your Application Pool and double click the Managed PipeLine Mode.
Set the Manage Pipeline mode from Integrated to Classic.
Set IIS7 Application Pool Defaults
You can also set the Manage pipeline mode in the Application Pool Defaults. You can do this in IIS7 by clicking on Set Application Pool Defaults.
And then change the Managed Pipline Mode to Classic.
The other way is changing your web.config to work with IIS7. You can get more information about this by reading this post.