Logic App Standard Blob trigger experiencing delay in picking files from Azure Blob Storage

Question

We are facing a performance issue with an Azure Logic App (Standard) workflow.

The workflow uses an Azure Blob Storage trigger (In-Built) to pick up files from a container. Recently, we are seeing significant delays where files remain in the container for a long time before the workflow is triggered.

Key details:

• Logic App Type: Logic App (Standard)
• Trigger: Azure Blob Storage trigger
• Storage Account: ADLS Gen2 (public network access enabled)
• Environment: Production
• Issue: Trigger latency / delayed pickup of files
• No authentication or connectivity errors observed
• No recent configuration changes

We have reviewed the App Service Plan metrics for the Logic App Standard.

The App Service Plan is WS2 with 2 instances. CPU utilization averages around 7–8%, memory usage is around 55–60%, and there is no indication of resource saturation or heavy load.

Despite this, all workflows using the Azure Blob trigger are experiencing significant delays, in some cases not triggering even after 24 hours. Files remain in the storage container without being picked up.

This indicates the issue is not related to scaling or resource constraints but may be due to platform-side Blob trigger latency or trigger listener issues.

Earlier, the same workflow was picking up files almost immediately. Now, the delay is inconsistent and impacts downstream processing.

Has anyone experienced similar trigger latency with Logic App Standard? Are there any recommended configurations, scaling guidelines, or known platform limitations?

Answer 1

Hi @G Pavan Kumar

Thank you for reaching out to Microsoft Q&A.

Yes, this behavior can occur with Azure Logic Apps (Standard) that use the Azure Blob Storage built‑in trigger, and it is a known pattern rather than a capacity issue in most cases.

Based on the details you shared (low CPU/memory usage, WS2 plan with multiple instances, no connectivity errors), the delayed or non‑firing Blob triggers are typically caused by trigger architecture limitations and container scanning behavior, not by App Service Plan saturation.

In order to resolve this issue:

Narrow the Blob trigger scope (quick mitigation)

Configure the trigger with a specific folder path and file pattern, for example:

container/subfolder/{name}.csv

Avoid using the container root wherever possible.

This reduces listing and scan overhead.

Restart or re‑publish the Logic App (temporary workaround)

Restarting the Logic App can re‑initialize trigger listeners.

This often restores triggering temporarily but is not a long‑term fix.

Use Event Grid instead of Blob polling

For production systems with latency sensitivity, Microsoft recommends using an event‑driven architecture:

Configure Azure Blob Storage → Event Grid for BlobCreated events

Route events to:

Logic App with Event Grid trigger, or

Logic App HTTP trigger

Ref: https://learn.microsoft.com/azure/connectors/connectors-create-api-azureblobstorage

Answer 2

The issue of delays in the Azure Blob Storage trigger for your Logic App (Standard) can be attributed to several factors. Here are some considerations and troubleshooting steps you can take:

1. Trigger Configuration: Ensure that your trigger is configured correctly. Sometimes, the polling interval can affect how quickly files are picked up. Check if there are any settings related to the polling frequency that might need adjustment.
2. Performance Factors: Since you mentioned that the issue is inconsistent, it could be related to the load on the Azure Blob Storage service or the Logic App itself. Consider monitoring the performance metrics for both the Logic App and the storage account to identify any spikes in usage or throttling.
3. Scaling: If your Logic App is under heavy load, consider scaling it. Azure Logic Apps (Standard) can be scaled out to handle more requests. You might want to review the scaling guidelines provided by Microsoft to ensure your Logic App is adequately provisioned for your workload.
4. Known Limitations: There may be platform limitations or known issues affecting the performance of triggers. It’s beneficial to check the Azure updates or the Azure Logic Apps documentation for any announcements regarding performance issues or maintenance that could impact your workflows.
5. Monitoring and Diagnostics: Utilize the monitoring tools available in Azure to check the trigger history and see if there are any patterns or specific times when the delays occur. This can help pinpoint whether the issue is related to specific files or times of day.

By reviewing these aspects, you should be able to identify potential causes for the delays and take appropriate action to mitigate them.