How to trace IIS error 500

The best way to trace IIS error 500 is to enable all log detail on screen, edit your web.config to

<configuration>
    <system.webServer>
        <httpErrors errorMode="Detailed" />
        <asp scriptErrorSentToBrowser="true"/>
    </system.webServer>
    <system.web>
        <customErrors mode="Off"/>
        <compilation debug="true"/>
    </system.web>
</configuration>