Restarting App Pools in Plesk

Application pools in IIS manage the worker processes that handle requests for your websites. Restarting an app pool can resolve many common issues including memory leaks, hung processes, and application errors without affecting other sites on the server.

When to Restart an App Pool

You should consider restarting your application pool when:

1. Your website returns 503 Service Unavailable errors
2. ASP.NET applications become unresponsive or slow
3. You have deployed new application code or updated configuration files
4. Memory usage for your site has grown unusually high
5. After installing or updating NuGet packages or dependencies

How to Restart via Plesk

1. Log in to your Plesk Control Panel
2. Navigate to Websites & Domains
3. Click on the domain whose app pool you want to restart
4. Click Hosting & DNS and then Hosting Settings
5. Locate the Application Pool section
6. Click the Restart button next to the pool name
7. Wait 10-15 seconds for the pool to fully recycle

Tip: After restarting, load your website in a browser to verify it is responding correctly. The first request after a restart may be slower as the application warms up.

Restart via IIS Manager (Advanced)

If you have RDP or administrative access:

1. Open IIS Manager (inetmgr)
2. Expand the server node in the left panel
3. Click Application Pools
4. Right-click on your site's app pool
5. Select Recycle for a graceful restart, or Stop then Start for a full restart

Understanding Recycle vs Stop/Start

• Recycle: Gracefully spins up a new worker process while the old one finishes existing requests. Recommended for production sites.
• Stop/Start: Immediately terminates the worker process. Use only when recycle does not resolve the issue.

Configuring Automatic Recycling

Plesk allows you to set automatic recycling schedules:

1. Go to Websites & Domains > your domain > Hosting Settings
2. Under Application Pool Settings, configure:

- Regular Time Interval: Recycle every N minutes (default: 1740)

- Virtual Memory Limit: Recycle when virtual memory exceeds threshold

- Private Memory Limit: Recycle when private memory exceeds threshold

Tip: Setting a private memory limit of 512 MB to 1 GB is a good practice for most ASP.NET applications to prevent memory leaks from impacting performance.

Troubleshooting

App Pool Stops Immediately After Starting

• Check the Event Viewer for application errors
• Verify your .NET CLR version matches your application requirements
• Ensure the app pool identity has correct permissions on the site directory

503 Errors Persist After Restart

• Check if the app pool is set to Stopped in IIS Manager
• Review Rapid Fail Protection settings — if the app crashes repeatedly, IIS disables the pool
• Check application logs for unhandled exceptions during startup

Cannot Find the Restart Option

• Ensure your hosting plan includes IIS application pool management
• Contact support if the option is not visible in your Plesk panel

Related Articles

• Plesk Panel Overview
• Troubleshooting ASP.NET Applications

If you continue to experience issues after restarting your app pool, please contact our support team at {{SUPPORT_EMAIL}} or open a ticket at {{SUPPORT_URL}}.