Logic App did not trigger issue

Question

Logic App did not trigger issue

Karthik K Koneru 81

Hi, I have an APIM API which puts message into Azure Servicebus Queue and later this message is consumed by Logic Apps. All of a sudden Logic apps did not trigger or consume the messages and all messages were sat in the Queue for 3.5 hrs which caused issue at our facilities. I have searched app insights of logic apps and could not find any failures or errors. Where as APIM do not have any issues with Servicebus and able to see messages sent successfully. I'm thinking it could be due to some network issue between Logic apps and Servicebus. How do I identify the root-cause of Logic apps not triggered?


Time	Event
5:34 AM	APIM starts successfully sending messages to Service Bus
5:34 AM – 8:59 AM	Messages queue up, but Logic App does not trigger
8:59 AM	Logic App finally triggers and starts processing messages

hossein jalilian 13,360 Reputation points Volunteer Moderator

2025-08-29T16:56:41.2066667+00:00

Hello Karthik K Koneru,

Thanks for posting your question in the Microsoft Q&A forum

It is usually caused by configuration or platform issues rather than a simple network outage. Common reasons include the Logic App being paused or misconfigured, Service Bus throttling or lock duration limits, cold starts on consumption plans, or problems with private endpoints and VNET integration. Even if Application Insights shows no failures, gaps in trigger polling, resource health issues, or connector misconfigurations may explain the delay. The best way to diagnose is by reviewing Service Bus and Logic App metrics, checking resource health and logs for downtime events, verifying connector settings, and ensuring path and polling configurations are correct.

Please don't forget to close up the thread here by upvoting and accept it as an answer if it is helpful
Karthik K Koneru 81 Reputation points

2025-08-29T18:10:16.84+00:00

Thank you Krishna @Krishna Chowdary Paricharla
Logic App's JobHost,runtime environment,Service Bus listener for logicapp was stopped at 5:31 AM and got restarted at 8:58 AM. Hence Logic App was offline/inactive for ~3.5 hrs. All the messages sent by facilities during that time frame were queued in Service Bus waiting to be picked up.
How to identify what caused the Logic App's JobHost, runtime environment, Service Bus listener to be stopped and restarted?
Krishna Chowdary Paricharla 2,915 Reputation points Microsoft External Staff Moderator

2025-09-01T09:42:04.7+00:00

Hello Karthik K Koneru,

Could you please check the private message and provide the required details for troubleshooting the issue further.

Here is the reference link on how to access & data retention policy of private messages in Microsoft Q&A.

Answer accepted by question author

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hossein jalilian 13,360 Reputation points Volunteer Moderator

2025-08-29T16:56:41.2066667+00:00

Hello Karthik K Koneru,

Thanks for posting your question in the Microsoft Q&A forum

It is usually caused by configuration or platform issues rather than a simple network outage. Common reasons include the Logic App being paused or misconfigured, Service Bus throttling or lock duration limits, cold starts on consumption plans, or problems with private endpoints and VNET integration. Even if Application Insights shows no failures, gaps in trigger polling, resource health issues, or connector misconfigurations may explain the delay. The best way to diagnose is by reviewing Service Bus and Logic App metrics, checking resource health and logs for downtime events, verifying connector settings, and ensuring path and polling configurations are correct.

Please don't forget to close up the thread here by upvoting and accept it as an answer if it is helpful
Karthik K Koneru 81 Reputation points

2025-08-29T18:10:16.84+00:00

Thank you Krishna @Krishna Chowdary Paricharla
Logic App's JobHost,runtime environment,Service Bus listener for logicapp was stopped at 5:31 AM and got restarted at 8:58 AM. Hence Logic App was offline/inactive for ~3.5 hrs. All the messages sent by facilities during that time frame were queued in Service Bus waiting to be picked up.
How to identify what caused the Logic App's JobHost, runtime environment, Service Bus listener to be stopped and restarted?
Krishna Chowdary Paricharla 2,915 Reputation points Microsoft External Staff Moderator

2025-09-01T09:42:04.7+00:00

Hello Karthik K Koneru,

Could you please check the private message and provide the required details for troubleshooting the issue further.

Here is the reference link on how to access & data retention policy of private messages in Microsoft Q&A.

Answer 1

Hello Karthik K Koneru,

When Logic Apps stop triggering from Service Bus without showing errors, it usually points to a listener/subscription issue rather than a network problem. A few things to check for root cause:

Service Bus Trigger Latency / Lockups
- In Consumption Logic Apps, the Service Bus trigger relies on polling. If the polling infrastructure in your region was delayed, messages can sit in the queue until the polling resumes.
- In Standard Logic Apps, the Service Bus connector uses the underlying worker (hosted in your App Service Plan or ASE). If the worker was cold-starting, overloaded, or paused (scale-in, app service restart, quota limits), the trigger may not have fired until the host became healthy again.
Platform / Regional Incidents
- Sometimes Azure backend throttling or transient outages can delay trigger execution. Check Azure Service Health for any incidents during the 5:30–9:00 AM timeframe.
Runtime Diagnostics
- Enable Diagnostic Logs and Trigger History in Logic Apps. This will show if the trigger execution was skipped, throttled, or delayed.
- In Application Insights, run a query for traces with operation_Name == "ServiceBusTrigger" to see if the trigger was being attempted during the downtime.
Connection & Authentication Issues
- If the Service Bus shared access signature (SAS) key or Managed Identity token refresh was delayed, the trigger may not have been able to authenticate until it refreshed successfully.
Recommended Next Steps
- Turn on Trigger Metrics (Run History → Trigger Outputs) to confirm if trigger fired late or didn’t fire at all.
- Configure dead-letter queues (DLQs) and alerts to detect build-up early.

For your reference, please refer the below documentation:

Troubleshoot and diagnose workflow failures in Azure Logic Apps

Connect to Azure Service Bus from workflows in Azure Logic Apps

Hope this helps!

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