Check this out: Implementing a Custom Error page on an ASP.Net website
Also, it looks like you're missing ".aspx" at the end of your page paths.
Pregunta
Getting internal server error... want to redirect page on error "404 Page not found".
<?xml version="1.0"?>
<configuration>
<system.web>
<urlMappings enabled="true">
<add url="~/Error404" mappedUrl="~/Error404.aspx"/>
</urlMappings>
<pages controlRenderingCompatibilityVersion="4.0"/>
<customErrors mode="on" defaultRedirect="~/Error404">
<error statusCode="404" redirect="~/Error404" />
<error statusCode="500" redirect="~/Error404" />
</customErrors>
</system.web>
<system.webServer>
<httpErrors>
<remove statusCode="404" subStatusCode="-1" />
<error statusCode="404" path="/Error404" responseMode="ExecuteURL"/>
</httpErrors>
<modules runAllManagedModulesForAllRequests="true" />
</system.webServer>
</configuration>
No hay solución correcta
Otros consejos
Check this out: Implementing a Custom Error page on an ASP.Net website
Also, it looks like you're missing ".aspx" at the end of your page paths.