Why are Robots going unresponsive ever since the Orchestrator app service is migrated?
Issue Synopsis:
Sometimes during a migration or upgrade activity, the Azure app service Orchestrator (single instance) might scale up automatically which essentially enables zone redundancy that requires at least 3 instances in the App Service plan.
This causes inconsistencies in the behavior of the application of the Robots with respect to license retrieval, connectivity with the Orchestrator, etc.
Resolution: There are 2 approaches to resolve this,
Approach #1 - Disable Zone Redundancy:
Zone redundancy requires at least 3 instances in the App Service plan, so scaling down might not be an option. In this scenario, create a new App Service plan without zone redundancy and move the WebApp to this new plan. This document includes instructions on how to create a new App Service plan without zone redundancy and how to move an app to another App Service Plan: Manage an App Service plan in Azure. This will allow, to have scaling set to 1.
Approach #2 - Enable Redis:
The approach here is to install Azure Cache for Redis and configure your WebApp with the configuration mentioned here: How to Configure Azure Cache for Redis in Orchestrator WebApp.
(Note: The "LoadBalancer.Enabled" setting has been deprecated in the latest versions).