Null Byte Injection in ASP.NET 4.7

I enabled <customErrors> section of the web.config file in ASP.NET application.

code: <customErrors mode="On" defaultRedirect="~/Errors/Error.aspx">

DAST scan reports the below Null Byte Injection vulnerability, kindly advise on the fix.

Unusual behavior by null characters injection can introduce vulnerabilities within the system or application scope. Attacker can manipulate a request to execute or read a system file.