Assume that you have an Ubuntu operating system virtual machine (VM) that's running behind a Microsoft Azure Load Balancer (ALB). After you update the Microsoft Azure Linux Agent to version 2.2.16 through the package manager, the ALB marks the Ubuntu nodes as offline even if they are accepting connections.
Note This issue applies only to Ubuntu version 14.04, 16.04, and 17.04 VMs.
This issue is fixed in Azure Linux Agent version 2.2.17. See How to update the Azure Linux Agent on a VM.
For more information about this issue, see the following article on the GitHub website:
OS.EnableFirewall=y breaks load balanced sets probing...
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