Handle "A potentially dangerous Request" in IIS

I have hosted an MVC web application in my local system. When my application was tested using a VAPT tool by external Auditors, they discovered an error when they accessed the application using the following URL : https://10.25.71.117/uncpath/<script>alert("123")</script>.

The error is:

"A potentially dangerous Request. Path value was detected from the client (<)."

Here my application is not uncpath. As my application itself is called, I want to handle the error through IIS server. For that I need to know the Error status code for this kind of requests and handle it using a custom error.

I think you want something like Custom error pages:

• https://learn.microsoft.com/en-us/iis/configuration/system.webserver/httperrors/
• Custom 404 error page not working on IIS 8.5

If you try but fail to implement, feel free to post your attempt(s) here and their results.