.net Web App recycles every 10 minutes unless fcnMode set to disabled in Web.Config

Question

Starting on Tuesday 5/6/2025 at 3:13ET my Azure hosted (US East) .net web app recycles every 5-10 minutes. It is not consistent. There were no code changes at this time. There are no file changes in wwwroot. The only way to get it to stop recycling is set fcnMode="Disabled" in web.config.

Answer 1

Hi Michael Fitzback,

Lets follow few troubleshooting steps below:

1. Look into your application pool's recycling settings. The default configuration in IIS can recycle the app due to memory limits, request limits, or time intervals. You might want to adjust the memory, privateMemory, or requests attributes in your recycling/periodicRestart settings if they're set too low.
2. Sometimes, changes to the web.config file are treated as a signal to recycle the app. Double-check that no settings have been changed that could prompt this behavior.
3. ASP.NET can recycle the application domains for various reasons including memory pressure or configuration changes. Ensure that your app isn't facing memory allocation failures or other high-memory conditions, which could trigger unplanned recycle operations.
4. As a default, periodic restarts are scheduled for app pools for health. If your application isn't designed to handle this gracefully, it might be causing issues.
5. Review your application for large objects or sessions being held in memory longer than necessary. This might help with the recycling frequency.

applicationpools/add/recycling/

recycling/periodicrestart/

recycling/periodicrestart/schedule/add

If you have any further assistant, do let me know.