VMs not restarting properly in Server 2016 RRS feed

  • Question

  • I have several VMs running in Hyper-V on Server 2016 that we shutdown remotely and then reboot the host. They're all configured to automatically restart upon the host's reboot, with a startup delay varying between 30 and 600 seconds (each VM is different). 

    SOME of the VMs will happily restart.  SOME of the VMs do not start at all.

    Looking in the Hyper-V event logs, there are absolutely no errors or complaints logged at all. It's as if it never even tries to restart those VMs. 

    We're not doing anything weird storage-wise; all VMs are using the same HDD storage area. We're well within the available RAM of the host machine (128GB). There's nothing odd about their boot options. Several of these VMs are identically configured to each other, and one will start while the other won't. 

    What in the world is going on?

    Sunday, December 24, 2017 3:53 PM


All replies

  • What do you mean when you say that your VMs won't start ? Is it on the Hyper-V interface (no poweron ?) or when the OS boot ?
    Sunday, December 24, 2017 4:59 PM
  • Hi jdsok,

    1. What are the OS of the VMs that do not start up automatically with "Automatic start Action" configured?

    2. Do you patched the Host and the VMs with the latest windows update, if not, please install updates on them;

    3. Please check the Hyper V VMMS event log, check what logs are recorded during the startup process;

    In additional, When the Hyper-V Server is restarted, the following events occur:

    1.Hyper-V initializes hypervisor code on the hardware.
    2.Hypervisor creates virtual environment.
    3.After creating the Virtualization environment, the control is returned to the Parent Partition.
    4.The Parent Partition, in turn, returns the control to its component called VMMS.exe or Hyper-V Virtual Machine Management Service.
    5.VMMS.exe is a multi-threaded application. It can initialize and start a virtual machine and get the control back to initialize and start other virtual machines. VMMS.exe does not have to wait for the virtual machine to be up and running before starting the next one. VMMS.exe performs two operations for a virtual machine at start up; (1) initialize the virtual machine to make sure its VHD files and configuration files are intact and (2) Start the virtual machine.
    6.VMMS.exe initializes and starts the virtual machines based on the following logic:
    Filter all the virtual machines which are set to always start automatically or using “Always start this virtual machine automatically” option.
    Filter all the virtual machines which have been configured with “Automatically start if it was running when the service stopped” option.
    Get the “Startup Delay” value for the virtual machines which are using above two options.
    Get all the virtual machines which are using “Nothing” option.
    Once VMMS.exe has the list of virtual machines, it performs the following logic to start these virtual machines: Start all the virtual machines for which “Startup Delay” is set to ZERO. That means do not wait for seconds to elapse and start the virtual machines immediately.
    Initialize all the virtual machines for which “Startup Delay” is set to a value other than ZERO and wait for the seconds to elapse before starting the virtual machines.
    Initialize all other virtual machines which are using “Nothing” option but do not start them.

    Best Regards,


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    Monday, December 25, 2017 7:58 AM
  • 1. This happens every time the host server is rebooted, and it's a different random assortment of VMs every time (it's not consistent). VM OSes are 2012R2, 2016, and ubuntu. 

    This happens on both of our Server 2016 Datacenter hypervisors. Our 2012R2 hosts do not have this problem.

    2. Yes, all are fully up to date.

    3. I've looked at all of the logs on the host, and I see the successful VMs being initialized and started. The unsucceesful VMs have no errors logged (nothing logged at all, like they don't even exist). 

    I thought at first it was tied to the startup delay, but that doesn't seem to matter either, as some VMs with longer delays started up just fine, along with VMs with shorter delays than the rest. 

    Last week (last reboot), only 3 out of 16 of my VMs didn't restart. This week, it was 7 out of 16. (Across two different 2016 Servers, 8 VMs on each, servers were installed and configured identically, all hardware is identical too.)  There were only 2 VMs that didn't start up both weeks. (Some didn't restart last week, but did this week, and vice versa.)

    Without any errors in the hyper-v logs, I'm at a loss.

    Tuesday, December 26, 2017 3:19 AM
  • Hi jdsok,

    Since it is a random number of VMs that not start up automatically and there's no error log recorded, it's hard for forum guys to guess the cause and troubleshoot. If you want to get better help, it's recommended to open a case with MS, so that they can have more channel to access your environment and do further research, here is the link to open a case with MS:

    Best Regards,


    Please remember to mark the replies as answers if they help.
    If you have feedback for TechNet Subscriber Support, contact

    Thursday, December 28, 2017 7:39 AM
  • I have the same exact problem with TWO hyper-v 2016. After reboot, VM (Win 2012) do NOT start! It's an hell after every win update...

    Wednesday, May 16, 2018 7:41 AM
  • Same situation here.

    Any updates on this? A possible solution?

    with best regards



    Thursday, June 14, 2018 8:03 AM
  • Hi Everybody

    Exactly same issue here with Win Server 2016



    Cedric Beaumois

    Sunday, July 15, 2018 6:54 AM
  • I have noticed the issue on my 2016 host. The VHDX disks that I made on the host don't start at reboot.

    This causes an issue with the hyper v servers that are dependant on them they stay in a save state.

    I have to go into disk manager and attach each vhd manually and then had them back as physical disks in hyper v.  I think I am going to add the as vhd disks to see if they then auto start at reboot.

    Monday, July 23, 2018 1:51 PM
  • Have had the same issue on Win 2016. No Log entry in Event Viewer. Some VMs are just not starting after reboot.

    In my case there were 2 possible reasons:

    - Another Hypervisor host had the same SID, tue to cloning the host images previsouly. Both hosts with the same SID were replicating some VMs to each other. Both hosts didn't start some VMs randomly.
    - Config version was 5, all the VMs (Ubuntu 18.04 Server) were from an Export from Win 2012. 

    What i have done:

    - I re-ran sysprep with the tick box, so it generated a new SID. Reset hostname, rejoin domain, reconfigure Network Inferfaces.
    - I deleted and re-created the VMs but keep the existing .vhdx HDD. Config Level is now 8.

    Since then, all the VMs are starting properly after every reboot. so far.

    Friday, August 17, 2018 12:13 PM
  • I tried to set VM startup delay to 0 seconds.

    I think all VM are starting now.

    I will try some reboot and I 'll keep you informed,




    Cedric Beaumois

    Thursday, December 20, 2018 6:59 AM
  • I am also getting this same issue when my 2016 HyperV host is automatically rebooted after patching during the night. half of the VMs are left in a suspended state while others are restarted just fine.
    Thursday, December 20, 2018 9:18 AM
  • Hi,

    someone know if this issue is solved by lasts cumulative updates ?



    Cedric Beaumois

    Thursday, May 2, 2019 11:24 AM
  • Hi,

    someone know if this issue is solved by lasts cumulative updates ?



    Cedric Beaumois

    No it isn't I perform monthly updates across my estate and have this issue, it can take 20-30 minutes for the first guest to start after a host reboot, I did wonder if it was because I have domain joined my hosts, and the only DCs are virtualised, the first guests I start are the DCs and they stick in the starting state, then start. Once all my guests are up and running they work fine. Can be rebooted without issues. It's just the initial startup after a host reboot that causes issues and no CU has fixed it. Nothing recorded in the Event Viewer, we flattened the primary VHOST and reinstalled it from scratch reattaching the existing guests, and this had no positive effect.
    Monday, May 13, 2019 2:09 PM
  • I have a similar issue in my production environment. We are currently migrating our Hyper-V servers from Windows 2008R2 to Windows 2016 and after each patch day it the server installs specific patches which trigger chained reboots (more than 1 reboot) I always find that after the first reboot the Hyper-V does not shut down cleanly the Virtual Machines and Kernel-Power Event 41 is logged on the VMs stating that the system rebooted without cleanly shutting down.

    This never happened on the old 2008R2.

    Friday, May 17, 2019 11:12 AM
  • Hi everybody,

    I read somewhere that if you configurer VM startup delay to : 0 seconds, all VM are starting well.

    I checked and it is OK in our environment.

    I also read that this VM starting issue disappear if we convert VM guest in release 8.0 version.

    Perhaps this issue appear only with 5.0 VM version on 2016 Hyper-v hosts.



    Cedric Beaumois

    Thursday, October 24, 2019 11:55 AM