How to tracing the Failed Requests
To start a new trace, perform the following steps:
1 – Logged in to Plesk.
2 – Go to Websites & Domains.
3 – Click on Failed Request Tracing.
4 – Click on Start Tracing.
You can start a new trace by specifying one or more HTTP status codes and the IIS component or components for which failed request files will be created. Once a trace is started, you can change these settings at any time.
5 – Click OK