How to resolve "It is an error to use a section registered..." error message on your ASP.NET site.

Programming, error messages and sample code > ASP.NET
If your ASP.NET site receives the following error message:

Configuration Error
Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.

Parser Error Message: It is an error to use a section registered as allowDefinition='MachineToApplication' beyond application level.  This error can be caused by a virtual directory not being configured as an application in IIS.

If your site is running off a sub folder like(, then it's very likely that your sub folder is not an application.  To fix this, you can login to your control panel-> ASP.NET Manager and set your sub folder as an application.