Backend Server Health Status Conflicting with Health Probe Logs in Application Gateway

Arunkumar Elango 0 Reputation points
2024-12-24T13:46:34.7533333+00:00

Hello Azure Community,

I am encountering an issue with my Azure Application Gateway where the backend server status is reported as Healthy, but the health probe log indicates that the server cannot be reached. The log states:

"Cannot connect to the backend server. Check whether any NSG/UDR/Firewall is blocking access to the server. Check if the application is running on the correct port.

However, the instance health is displayed as Healthy in the pipeline results.

Here are some additional details:

  1. A Virtual Machine Scale Set (VMSS) is being used as the backend server.
  2. The health probe is configured correctly to target the expected endpoint.
  3. Network Security Groups (NSGs) and User-Defined Routes (UDRs) appear to be correctly configured, but the error persists.

Please provide insights on why this discrepancy might occur and steps to troubleshoot or resolve it.

Attached is the DevOps Pipeline log in image format for your reference. Please find it attached.
Thank you in advance...!

Regards,
Arunkumar Elango

Azure Application Gateway
Azure Application Gateway
An Azure service that provides a platform-managed, scalable, and highly available application delivery controller as a service.
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Azure Virtual Machine Scale Sets
Azure Virtual Machine Scale Sets
Azure compute resources that are used to create and manage groups of heterogeneous load-balanced virtual machines.
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