[RESOLVED]'System.ArgumentException' occurred in System.Web.Mvc.dll – Additional information: Return type 'System.String' is not supported.

i am getting below exception when i try to execute my asp.net mvc 5 application.

see the exception please.

An exception of type 'System.ArgumentException' occurred in System.Web.Mvc.dll but was not handled in user code

Additional information: Return type 'System.String' is not supported

Hi, softech.empl..

Please provide code.


Hi softech,

First, please try to create a new MVC project and run it to check whether it works fine.

Secondly, please use this command to install or update MVC package:

Install-Package Microsoft.AspNet.Mvc -Version 5.1.1

If you still have the issue, please share the project on the OneDrive.

Best Regards

Starain Chen

Leave a Reply