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.
Вопрос
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>
Нет правильного решения
Другие советы
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.