Troubleshoot changing the backend port for an existing load-balancing rule of a load balancer that has a virtual machine scale set deployed in the backend pool

Summary

When a load balancer is configured with a virtual machine (VM) scale set in the backend pool, you can't directly modify the backend port of an existing load-balancing rule while it's associated with a health probe. This article explains how to remove the health probe, update the backend port, and then reconfigure the health probe to allow the change to take effect.

Cause

When a load balancer is configured with a VM scale set, you can't modify the backend port of a load-balancing rule while it's associated with a health probe.

Solution

To change the port, you can remove the health probe. Update the VM scale set, update the port, and then configure the health probe again.