While trying to upgrade the Altiris Client Task Server Agent, the Symantec Management Agent service is unable to stop or restart in a timely fashion. IIS Console becomes unresponsive on those servers that have IIS installed. As well if we check the Task Manager, we could see two AtrsHost.exe OR AeXNSAgent.exe processes running, while one of them was not stopping even after trying to kill the process.
If we check the Services on the Task Server, The World Wide Web Publishing Service is unable to stop:
"The World Wide Web Publishing Service (W3SVC) remains in a "stopping" state, but cannot fully stop or it cannot be restarted." (Source: KB4338815 or KB4338818)
Known issue introduced by similar Microsoft patches like KB4338818. Note: There are different KB numbers related to this like KB4338815, KB4338818, KB4338823, KB4338824
During the Altiris Client Task Server Agent upgrade process, IIS is been called to stop and restart in order to create the proper references with virtual directories and AppPools. Having the World Wide Web Publishing Service in a "stopping" state causes the Symantec Management Agent to be unstable and partially upgraded.