Parser Error Message: The virtual path '/common/footer.ascx' maps to another application, which is not allowed.

Issue: I am getting this error when I try to run my ASP.NET application on my Windows hosting server. Parser Error.

Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parser error details and modify your source file appropriately.

Parser Error Message: The virtual path '/common/footer.ascx' maps to another application, which is not allowed.

Source Error:
Line 1: 
Line 2: 
Line 3: 

Solution :
 
If the .ascx file is in one folder configured as an application in IIS, and the page from which you're trying to use it is in a different IIS application, it won't work. User controls cannot be used across app domain boundaries, which is one of their weaknesses compared to custom server controls.

To solve this you can:
- Copy the .ascx file to a folder in the application from which you want to use it, which of course means that you now have two copies of the User Control to maintain.

Or

- Create a custom server control with the same functionality, give it a strong name, and install it in the Global Assembly Cache (GAC). Now you can use this control from any app on that machine.
 
More details can be found at :
http://authors.aspalliance.com/stevesmith/articles/netreuse1.asp