Azure App Service
Azure App Service is a service used to create and deploy scalable, mission-critical web apps.
I've worked round the issue by implementing my own logging for the stuff I need
Azure IIS Logging has stopped working
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FJT
5
Reputation points
Hi
My IIS logs stopped logging to the file system at 09:29 on 15/8/25.
I am not seeing any new logs in the LogFiles/http/RawLogs folder. I have tried restarting the site, and switching logging off and on. I have also deleted and recreated the folders. I have 'owner' role on the website (I am the only account with access). No activity shows in 'view log stream' for web server logs either.
Nothing on the site had changed. It's a simple webapp on a free subscription and has been running for about a year without issues.
Any pointers gratefully received!
Azure App Service
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Anonymous2025-08-18T22:44:14.6933333+00:00 Hello @FJT ,
Thank you for submitting your question on Microsoft Q&A.
Here’s why your IIS logs may have stopped writing in Azure App Service, and how you can resolve it efficiently the main causes are
Free Tier Storage Limit :- The Free App Service plan offers about 1 GB of storage. Once this limit is hit, logging stops automatically. IIS logs can fill up space quickly.
Automatic Logging Disable :- Application Logging (Filesystem) disables itself after 12 hours, designed for temporary debugging. For ongoing logging, it will stop unless re-enabled.
Log Retention/Quota Settings :- IIS logs follow quota and retention rules. If the quota is exceeded, older logs are deleted, and logging can pause until space is available.
Platform Updates :-Azure App Service instances can restart or move. If logs are stored only on the file system, they may not persist after updates.
Here we can try troubleshooting Steps
- Check disk usage in the Azure Portal under App Service > Quotas or through Kudu (D:\home\LogFiles).
- Review logging settings in Monitoring > App Service Logs and confirm Web Server Logging is set to File System or Blob Storage, and Application Logging is enabled as needed.
- Use the Kudu Console (Advanced Tools > Debug Console) to inspect LogFiles/http/RawLogs.
Here are better Solutions
- Free up space by deleting old logs from LogFiles using Kudu or FTP, or move logs to Blob Storage for better retention.
- Switch Web Server Logging to Blob Storage in App Service Logs to avoid quota issues and retain logs after restarts.
- Enable Application Insights for advanced monitoring and analytics. It’s free for basic use and more reliable than IIS logs.
- Restart your App Service after updating logging settings and clearing space to apply changes.
Free Tier Advisory
- Free tier has limited storage and no SLA for logging. For more reliable logs, upgrade to Basic or higher.
Ready to move IIS logs to Blob Storage or need an automated cleanup script? Let me know and I’ll guide you through it.
References link :-
Enable Diagnostic Logging - Azure App Service | Microsoft Learn
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Kurt Bachtold 25 Reputation points2026-03-20T03:33:53.58+00:00 We just ran into the same issue in one of our production services, but it is even more perplexing. In an App Service which is scaled to 2 servers, only 1 of the 2 servers is writing successfully to rawlogs. It seemed to have broken on 3/10/26 around midnight, where with no changes to the application deployment, now only one of the two instance log files is being generated. No amount of restart, refresh, code deployment, VIP swap or turning on/off the Application logs seems to fix it. I've switched between Off, File System, Blob storage for logging. No change. Only one of the two instances is generating log files. How are we supposed to diagnose and fix this?
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Andy Schmidt 10 Reputation points2026-03-20T04:16:14.91+00:00 I had the exact same problem as @fjt on the same date (15 AUG 2025), but it had recovered about a week later.
Now, just like @Kurt Bachtold , I have the problem again - starting around 3/11/2026.
@fjt : My AppService is hosted in their "Germany West Central" zone. Where is yours?
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2 answers
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FJT 5 Reputation points
2025-08-19T07:33:49.26+00:00 Thank you - I have tried those things and logging is still not working.
My disk usage is 2%
My logs are configured as follows -
My log files folder is empty (I previously deleted the logs that were there in an attempt to resolve the issue, but the files were small). I have restarted the application several times. It was all working as expected until a few days ago, and stopped when nothing had changed.
Is there anything I can do to get the logs going again?