After August update Hyper-v Win10VM crashes when connecting via RDP

Can anyone confirm this problem?
Windows 10 (1903) all updates running Hyper-V (gen2) windows 10 (1903) all updates VM.
When connecting via RDP (using windows remote desktop connection application) to that VM, it just crashes, in Hyper-v manager it shows constant 12% cpu usage and I can't connect to it or shutdown it, only forcefully shuting it down via "Turn off..." option works.
Physical PCs RDP work just fine.
All my windows 10 VMs with august update shows same behavior, if I roll back to snapshot before update it works fine.

VBJP said:

Can anyone confirm this problem?
Windows 10 (1903) all updates running Hyper-V (gen2) windows 10 (1903) all updates VM.
When connecting via RDP (using windows remote desktop connection application) to that VM, it just crashes, in Hyper-v manager it shows constant 12% cpu usage and I can't connect to it or shutdown it, only forcefully shuting it down via "Turn off..." option works.
Physical PCs RDP work just fine.
All my windows 10 VMs with august update shows same behavior, if I roll back to snapshot before update it works fine.

Hi there
@VBJP

Not sure exactly how HYPER-V works but I think you need to ensure that the VM connects to your LAN via an external switch (equivalent to Bridged mode). Default is NAT which always causes problems when LAN connectivity is required. The other possible issue is that default connection for Windows has SMB1 disabled --you might need to enable SMB1 depending on what's connecting to the VM. You also need to check that the VM allows RDP connections (default is no) --settings are in control panel (yes it's still available in Windows).

Cheers
jimbo

jimbo45 said:

Hi there
@VBJP
Not sure exactly how HYPER-V works but I think you need to ensure that the VM connects to your LAN via an external switch (equivalent to Bridged mode). Default is NAT which always causes problems when LAN connectivity is required. The other possible issue is that default connection for Windows has SMB1 disabled --you might need to enable SMB1 depending on what's connecting to the VM. You also need to check that the VM allows RDP connections (default is no) --settings are in control panel (yes it's still available in Windows).Cheersjimbo

Thank you very much for your reply.
For my VMs I am using external type switch and I have dedicated NIC to it different than NIC host OS uses.
I am not using default switch for anything.
And this setup worked without any problems before installing august updates.

Is not that I can not connect to VM, problem is when I try to connect VM just crashes.

Also problem occurs if I try to open VM in Enhanced session in Hyper-V manager VM just crashes and becomes unresponsive with 12% cpu usage constant.

VBJP said:

Can anyone confirm this problem?
Windows 10 (1903) all updates running Hyper-V (gen2) windows 10 (1903) all updates VM.
When connecting via RDP (using windows remote desktop connection application) to that VM, it just crashes....
All my windows 10 VMs with august update shows same behavior, if I roll back to snapshot before update it works fine.

Have I understood you correctly? Are both the Host machine and the VM running 1903, updated to the August CU 18362.295? And what about the machine trying to connect, is that 18362.295 too? RDP is something I rarely use, usually I connect to a VM on its host machine.

I have a Hyper-V VM running 1903 18362.295 on an 1809 Host machine which has had the August update for 1809. I can RDP connect to that from a fully updated W10 Home 1903 PC . My other 1903 (also fully up to date) Host machine has no 1903 VMs. but I can RDP to its (fully updated) 1809 VM.

To test you configuration (1903 host with 1903 VM) I had to export the 1903 VM from its 1809 host and import it to the 1903 machine. I can RDP to it from W10 Home without a problem.

Also problem occurs if I try to open VM in Enhanced session in Hyper-V manager VM just crashes and becomes unresponsive with 12% cpu usage constant.

I have tested that too, the 1903 host can open an enhanced session to its 1903 VM. Both host and VM are on the August update, build 18362.295.

I'm also experiencing similar problems starting last Friday after updates were installed with Windows 10 Pro x64 1903 host and guests. Enhanced sessions from host's Hyper-V Manager and also RDP sessions from host into VMs now lock up with ~12% continuous CPU showing in the guest VM.

Same problem occurs on two other systems that were fine until end of last week.

I've got some access into the VMs by using Hyper-V Manager with enhanced session disabled but I'm now getting BSOD's every few hours.

Salutations etc to the Nutella kid and co! Good work, haven't had BSOD for years!

Bree said:

Have I understood you correctly? Are both the Host machine and the VM running 1903, updated to the August CU 18362.295? And what about the machine trying to connect, is that 18362.295 too? RDP is something I rarely use, usually I connect to a VM on its host machine. I have a Hyper-V VM running 1903 18362.295 on an 1809 Host machine which has had the August update for 1809. I can RDP connect to that from a fully updated W10 Home 1903 PC . My other 1903 (also fully up to date) Host machine has no 1903 VMs. but I can RDP to its (fully updated) 1809 VM.
To test you configuration (1903 host with 1903 VM) I had to export the 1903 VM from its 1809 host and import it to the 1903 machine. I can RDP to it from W10 Home without a problem.
I have tested that too, the 1903 host can open an enhanced session to its 1903 VM. Both host and VM are on the August update, build 18362.295.

Thank you for taking your time to test.Yes, Hyper-V host and VM are 1903 with latest update, connecting client is same version
It seems that problem occurs only on second connection first time after starting VM I connect without problem, then close RDP client and try to connect again and at that time VM crashes

MontyP said:

I'm also experiencing similar problems starting last Friday after updates were installed with Windows 10 Pro x64 1903 host and guests. Enhanced sessions from host's Hyper-V Manager and also RDP sessions from host into VMs now lock up with ~12% continuous CPU showing in the guest VM.

MontyP said:

Same problem occurs on two other systems that were fine until end of last week. I've got some access into the VMs by using Hyper-V Manager with enhanced session disabled but I'm now getting BSOD's every few hours.

So I am not only one experiencing this. I can only blame august update because if I restore VM to snapshot without august update problem is gone.

Restoring to earlier snapshot also worked for me. Problem is that it's really hard to stop updates trickling in from MS. I've currently paused them until late September (being the longest I can pause them!) until MS recognize, identify and fix the problem.

VBJP said:

It seems that problem occurs only on second connection first time after starting VM I connect without problem, then close RDP client and try to connect again and at that time VM crashes

I'm having problems trying to reproduce that. I can connect the first time, but when I close the RDP client and try to connect again it says it cannot connect. When I then connect to the VM on the host machine I find the VM has lost its network connectivity.

So Glad I stumbled upon this post. I was pulling my hair out trying to figure out a solution. I just spun up Three Win 10 VM's last night on a brand new Server. All was good.

This morning after the updates I presume, I have the exact same issues! You can RDP in ONE time. Disconnect. When you try again, the screen freezes, CPU goes to 22%, and there is no way to recover except hard kill the VM. Has anyone found a fix yet, or do we just have to wait for a fix? Thanks!

- - - Updated - - -

Following up on my previous post, I removed KB4512508 from the Guest OS'es and I am back to working fine now. This is definitely an issue with this update.

gqchris said:

So Glad I stumbled upon this post. I was pulling my hair out trying to figure out a solution. I just spun up Three Win 10 VM's last night on a brand new Server. All was good.

This morning after the updates I presume, I have the exact same issues! You can RDP in ONE time. Disconnect. When you try again, the screen freezes, CPU goes to 22%, and there is no way to recover except hard kill the VM. Has anyone found a fix yet, or do we just have to wait for a fix? Thanks!

- - - Updated - - -

Following up on my previous post, I removed KB4512508 from the Guest OS'es and I am back to working fine now. This is definitely an issue with this update.

Thanks for that tip.
In the mean while, MS released (in the last 24 hrs) KB4512941 as a follow on to KB4512508. I tried it to see if it fixed the subject problem but, unfortunately, it didn't. -> Roll back KB4512508 and disable updates seems to be the way to go for now.