I've searched around and I've found lots of instances of users complaining about similar issues, but I don't think there is a single solution or reason for this issue - at least none that I can see, I need some help figuring this out.
Very frequently Windows will hang during the reboot process, but when I say hang it isn't exactly unresponsive; the system will stop most of its processes and functionality, but it will still have the kernel running, replies to ping requests, and even tries to negotiate RDP connections but then fails probably due to not being able to validate the login credentials... but for all intents and purposes the reboot process just stalls forever. If I open the ESXI web console, the servers will show their logon screen (actually, the clock and the message "Press CTRL+ALT+DEL to login"). The clock will be running accurately, but that's it. I cannot interact with it and the only solution is to force-reboot the VM. The host and guests are 3 years old, I can't really remember if this issue was always present (originally HPE ESXI 6.0) or if it has been brought on by recent updates (either ESXI, VM Tools, Windows, or a combination). At this moment I'm using the latest version of ESXI (v6.5 U3) and it's bundled VMWare Tools (v10.3.10 build 12406962).
This problem happens 6 out of 10 times, and it just happened last night with two guests hosted on the same server while they were installing and applying Windows' updates. There are also many instances where this happens when the reboot process is initiated from within an RDP session (unclear why), but this was definetely not the case here. After manually rebooting the VMs I checked the event viewer on both servers and they pretty much tell the same story, the updates are installed and then a restart is needed to apply (or rollback), services then begin to enter the "stopped" state and then nothing else happens. The servers keep running with most of their services stopped but never actually reboot on their own. The last recorded message on the event viewer is:
The operating system is shutting down at system time ....
I also looked at the VMware logs from ESXI but nothing seems to happen close to the time of the restarts which would raise any eybrow in particular.
I would appreciate if you could throw some ideas around about what could be causing this issue.
P.S: I'm attaching the Windows' system events logs from both guests just in case.