Timer and Queue Triggered Functions stopped without any errors

Question

My Azure Functions app has stopped executing all functions (both timer and queue triggered) on two separate occasions without any error messages or warnings. A manual restart resolves the issue temporarily, but it has now occurred twice at different times.

Environment Details:

Plan Type: Premium v2 (P2V2) with 2 instances. Always On: Enabled

Runtime Version: v4 (FUNCTIONS_EXTENSION_VERSION = ~4)

WEBSITE_TIME_ZONE: Not set, so expecting UTC

Function Details:

• 7 Timer-triggered functions with various CRON schedules sharing just one of them:
  • 0 */5 * * * * (expect to fire every 5 minutes)
• 10 Queue-triggered functions processing approximately 100 messages per hour
  • The connection to the storage queue is functional and queue is accessible

Invocation ID for the function that is expected to run every 5 minutes : 22693ec7-7ab0-40c5-a86d-3ce1800d2010, at 2026-01-19T14:07:16.1793312. Location : West Europe.

No deployment or configuration changes occurred before either incident or recently. No errors in Application Insights or Azure Portal diagnostics around the time (last execution for that function was at 2026-01-18T12:00:00.0151005Z) it stoppped.

Answer 1

Hi @Yash Seeta ,

Thanks for reaching out to Microsoft Q&A.

Here are a few things to consider and some steps to help troubleshoot the situation:

1. Function Runtime Host Issues: Sometimes, the function host may not be starting up correctly. You can check for any startup exceptions in Application Insights with the following query:

   
      exceptions
   
      | where customDimensions.Category == "Host.Startup"
   
   

2. Invocation Failures: If the function invocation starts but doesn't complete, you might want to look at exceptions during the execution. You can use this query:

   
      exceptions
   
      | where customDimensions.prop__functionName =~ "<YourFunctionName>"
   
   

3. Check for Other Function Apps: If there are other Function Apps pulling messages from the same queue, this might cause one to appear idle. Make sure that only one app is processing the queue if that's the case.
4. Diagnostics Logs: Since you've mentioned that no errors were found in Application Insights or other Azure Portal diagnostics, ensure that you check the function app logs for any silent failures. Here's a sample query for logs:

   
      AppServiceConsoleLogs_CL
   
      | where AppName_s =~ "<YourFunctionAppName>"
   
      | where Log_s contains "FunctionAppLogs"
   
   

5. Always On Setting: It's good that you have the "Always On" setting enabled, but ensure that your function app is running and that there are no unusual resource spikes.
6. Scaling and Load: Verify if the function app is under heavy load or if the plan is hitting its resource limits. Sometimes, functions stop responding if they are overwhelmed.

References:

• Investigating and reporting issues with timer triggered functions not firing
• Timer Trigger Troubleshooting
• Monitoring Azure Functions with Application Insights
• Check logs using Log Analytics

Hope this helps!

---

If the resolution was helpful, kindly take a moment to click on and click on Yes for was this answer helpful. And, if you have any further query do let us know.

Answer 2

It seems like your Azure Functions app is experiencing issues with executing timer and queue-triggered functions without any apparent errors. Here are a few potential reasons and troubleshooting steps you can consider:

1. Always On Setting: Since you are using a Premium plan with Always On enabled, this should generally prevent the app from going idle. However, ensure that the setting is correctly applied and functioning as expected.
2. Function Timeout: Check if your functions are hitting any timeout limits. Long-running functions can cause issues, and it’s essential to ensure they complete within the allowed time. For Premium plans, the timeout can be configured, but if functions exceed this, they may stop executing.
3. Execution Health: Use the diagnostic checks available in Azure to evaluate execution health. This includes checking for stuck or long-running executions, which could prevent new invocations from being processed.
4. Resource Constraints: Monitor the resource usage of your function app. High CPU or memory usage can lead to performance degradation or failures in executing functions. Ensure that your instances have enough resources allocated.
5. Application Insights: Although you mentioned no errors were logged, double-check the Application Insights configuration to ensure it captures all relevant logs. You can run specific queries to check for any hidden issues or patterns that might not be immediately visible.
6. Manual Restart: Since a manual restart temporarily resolves the issue, consider automating a health check that restarts the function app if it detects that functions are not executing as expected.

If the problem persists, you may want to reach out to Azure support for more in-depth diagnostics.

---

References:

• Resolve "Function App Down or Reporting Errors" issues
• Improve the performance and reliability of Azure Functions