Azure App Service
Azure App Service is a service used to create and deploy scalable, mission-critical web apps.
IS Web Server Logging (File System) stopped working on multiple Azure App Services since March 18
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The Pixel Shop
0
Reputation points
Hi,
I’m experiencing an issue with Azure App Service (Windows) where IIS Web Server Logging to File System has stopped working.
Details:
- Logging is enabled under App Service Logs → Web Server Logging = File System
- Logs were previously written to:
D:\home\LogFiles\http\RawLogs - Everything was working fine until March 18
- Since then:
- No new log files are created
- Existing files are not updated
- Applications are running normally and receiving traffic
This issue affects multiple App Services
This seems like it might be platform-related since multiple apps are affected simultaneously.
Any help or guidance would be appreciated.
Azure App Service
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Golla Venkata Pavani 3,415 Reputation points Microsoft External Staff Moderator2026-04-06T20:46:28.8266667+00:00 Thank you for reaching us regarding the issue When IIS Web Server Logging to the local file system suddenly stops.
App Service file system logging is best‑effort and not designed for long‑term or production use. The App Service file system (
D:\home) runs on ephemeral, multi‑tenant infrastructure, and log writing is not guaranteed to be continuous or durable. Platform maintenance, infrastructure updates, or instance recycling can cause IIS Web Server logs to stop being written without affecting application availability or traffic.Microsoft explicitly states that:- Web Server (IIS) logs written to the App Service file system are temporary
- There is no reliability or persistence guarantee for file‑system‑based logs
- File system logging should be used only for short‑term troubleshooting, not for ongoing monitoring
Recommended Approach:
Microsoft recommends using Azure Monitor via Diagnostic settings for IIS logging on Azure App Service, as it allows logs to be sent to Log Analytics, Storage, or Event Hub, providing durable storage, centralized monitoring, and better reliability compared to File System logging.Recommended Next Steps
- Do not rely on Web Server Logging > File System for production diagnostics.
- Configure Diagnostic settings on each App Service.
- Enable WebServerLogs and send them to Log Analytics or Azure Storage.
- Use Azure Monitor for querying, alerting, and retention.
Reference:
https://learn.microsoft.com/en-us/azure/app-service/troubleshoot-diagnostic-logs
https://learn.microsoft.com/en-us/azure/app-service/troubleshoot-diagnostic-logs#overview-of-logging-types
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