After Upgrading Aria Operations to 8.17.1 the System Status page displays "Unknown" Cluster status and the error below for the nodes.
"An error occurred while retrieving the list of nodes for this cluster. Check the logs for details."
However, regular UI show Cluster Management page fine.
Leave cluster to finish reloading page and webservices on its own. We have seen where large clusters have taken up to 3 hours to load the cluster page correctly. No additional steps need to be taken.