Identify the affected domain, pool name, outage time and recent deployment or runtime changes. A Plesk customer may need support to inspect Windows events. Keep a recovery copy of the previous application release and configuration.

1. Check the domain dedicated-pool state and record whether it is stopped or running. Review configured recycling, idle and resource limits.
2. Have the authorized administrator inspect Event Viewer Application and System events at the same time, including Windows Process Activation Service and application crash records.
3. Correlate the pool name, process ID and error with the website request. Distinguish invalid identity credentials, runtime or module startup failure, resource exhaustion and an application crash.
4. Correct the evidenced issue or restore a known good application release. Start or recycle only the affected pool during a controlled window.
5. Observe the next requests and resource trend. If a crash recurs, preserve the event and arrange an appropriate protected crash dump or developer investigation instead of restarting indefinitely.

Confirm the pool remains healthy over the workload that previously triggered the failure. Test application sessions and background work. Check that other applications sharing the pool are not the actual source of the crash.

Do not disable rapid-fail protection as a permanent workaround. Increasing memory or timeout thresholds can postpone symptoms while consuming shared resources. Crash dumps can contain secrets and customer data, so restrict collection, storage and sharing. If the change cannot be safely diagnosed live, recover the previous release and reproduce in a controlled environment.

• Configuring a dedicated IIS application pool in Plesk
• Hosting an ASP.NET Core application on Plesk for Windows
• Investigating a Windows service failure with Event Viewer
• Setting the default document for an IIS website in Plesk

• Plesk: Plesk For Windows Setting Up Iis Application Pool
• Microsoft: Process Termination Crash