It is necessary to restrict ChromeOS version upgrades to a particular version that has been fully tested with the version of the agentM app that you are running. Please check the release notes for the version that you are running to find out which ChromeOS version you should restrict the device to.
Please note that you need to restrict the version prior to the comissioning or turning your device on for the first time. If the device boots up and you have not applied this setting it can autoupdate to the latest version of ChromeOS without your knowledge.
See intructions below on how to find the version restriction setting in your Chrome Device Management Console.