Why did Azure Application Insights stop logging traces for 3 hours?

Question

For almost 3 hours (3:52 PM - 6:36 PM) no traces were logged in my Application Insights. During this time many requests were made that should have triggered the functions that log traces. How can I know if these functions executed as expected? And why were there no traces logged?

Traces (Notice gap between 3:52 - 6:36)

Requests (notice that all requests shown in the screenshot are made in the gap of the missing traces)

Answer 1

Hi Kuochuan Ponzio,

I would recommend checking Diagnostic Logs within your Application. If there is no sign of any issues or errors, I would recommend logging a ticket with Azure support:

https://azure.microsoft.com/en-us/support/create-ticket

Unfortunately what you have given in this post isn't verbose enough to give you any more diagnostics of the problem.

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If this is helpful please accept as answer or upvote.

Best regards,

Dillon Silzer | Cloudaen.com | Cloudaen Computing Solutions

Answer 2

This was due to results being limited to 1000 items in the Log Query editor.

Answer 3

Kuochuan Ponzio

Thanks for the update! Glad to see you were able to resolve your issue. Thanks for posting your solution so that others experiencing the same thing can easily reference this.

Since the Microsoft Q&A community has a policy that the question author cannot accept their own answer, they can only accept answers by others, I'll repost your solution in case you'd like to Accept the answer.

Issue:

Azure Application Insights stopped logging traces for nearly 3 hours, even though requests were made during that time.

Resolution:

The missing traces were due to the Log Query editor limiting results to 1,000 items. Refining the query to retrieve more results made the traces visible.

Essential Insights:

• Query result limits: Application Insights log queries have a default limit on the number of results returned. If data seems to be missing, try adjusting the query parameters.
• Diagnostic tools: Azure Monitor and Diagnostic Logs can help confirm if functions executed as expected.
• Workbooks & visualization: Understanding Azure Workbooks' data source limits can aid in better visualization and troubleshooting.

Hope this helps others facing similar issues!