Windows 11 VM on Parallels has broken virtual TPM.

We've been able to transfer the guest vm to VMware Fusion Pro for Mac (free) and with the TPM enabled and the latest update from Microsoft, all is working fine - so I'm not 100% convinced the issue is purely a Microsoft problem. Clearly whatever Parallels has done in terms of TPM emulation isn't compatible with what Microsoft are expecting, and surprisingly VMware does not exhibit the same issues.
 
I read that switching the Windows version to the older one would help- but since then there was another update released the latest update is 2026-07 Update (KB5121767) (26200.8894) and it does not resolve the problem either. I checked with Claude.ai and it suggested deleting the TPM and installing a new TPM and then adding the M365 credentials. I opened a ticket with Parallel support called them and sent them the Cluade.ai handoff - they should post it here as a solution for all if they think that route can work and there is no loss of data in the process (?). But they are unable to provide any solution but revert back to prior versions and wonder if that would compromise overall security (?). Does anyone have any thoughts- if it is of any value I can paste it here but that is what Claude.ai did after hours of digging around with Claude and CoPilot Pro ( not effective). Support also stated that Microsoft is working on this- and thus does that mean a solution will not come about till Microsoft fixes it (?). What if I were to reinstall the whole set up again- what if I am a new customer- even as a new customer on a fresh license I will not be able to operate? Sorry if my questions are nonsensical but I am only a user and not an engineer - just trying to get the services back on- having them off is affecting workflow deeply.
 
We had the same problem with the KB5101650 update. Once we'd uninstalled it, the virtual TPM 2.0 chip started working again. However, as the update is intended to fix many security issues, we hope that Microsoft will resolve the Parallels compatibility issue as soon as possible. Analysing the issue and finding a temporary solution really took up a lot of our time, which we were unable to use productively. How will we be informed once the problem has been resolved?
 
Once again, Parallels demonstrate this is not a Professional platform for getting work done. They should be testing the LCU and notifying us of any critical issues. Once issues like this land they should issue comms to all users immediately, diagnose it, explain to us why it broke, and give us an estimate as to when a fix may become available. But they will not do this. They won't even let us know if engineering are working on a fix, never mind provide an ETA. We just sit and wait for days or weeks or months, and eventually an update will come out to resolve it. If we are lucky they'll advise "don't update", which is no use at all to anyone in an organisation that has actual IT Security policy.
 
I am having the same problem now too. Would you please post the fixes you suggested to others in their "dedicated ticket" emails so we can try them?
 
The problem may also be with MS.

I have to run Hyper-V from Intune/Autopilot and if I patch the installation ISO/image to build 26200.8894 and run Autopilot from it, the TPM seems to be OK, but encryption and other things dependent on TPM do not work.
If I install from an older version of ISO/Image 26200.8655 and after installation the OS is patched to 26200.8894, everything works without a problem.

For macOS, I know that there is:
- working build 26200.8655 (KB5094126)
- non-working builds 26200.8894 (KB5121767), 26200.8875 (KB5101650)

Has anyone tested build 26200.8737 (KB5095093) (Preview)?
 
Would appreciated if someone from Parallels can chime in and give us an update. Is the problem being worked on? When can we expect an update/fix? Once the company forces KB5101650 my main workflow will be dead in the water. I of course can use O365 in a browser on the Mac to get some of the work done. But will be missing loads of work that needs to be done via local DB and/or spreadsheet data relating.
 
The company I work for forces the update as soon as it is uninstalled, rendering my Parallels VM for work effectively useless right now, so I very much feel your pain. I agree that it would be appreciated if someone from Parallels would chime in, but since this is a Windows bug, not a Parallels bug, I am not sure what Parallels can do other than acknowledge the issue and work with Microsoft to pursue a fix. Still, an official response would go a long way...
 
Same issue here -- Parallels Desktop 26.4.0 (57513), Windows 11 25H2 Build 26200.8875, broke after installing KB5101650 on 7/14. Get-Tpm returns the same 0x80280095 "Structure is wrong size" error, and it's breaking Microsoft 365 desktop app sign-in (error 657rx / sub status 6008) while Outlook Web keeps working -- matches everyone else's signature exactly.

Just submitted a support ticket referencing this thread and my technical report ID, in case it helps connect the dots faster on the engineering side.
 
ChristianP27 said:
I agree that it would be appreciated if someone from Parallels would chime in, but since this is a Windows bug, not a Parallels bug, I am not sure what Parallels can do other than acknowledge the issue and work with Microsoft to pursue a fix.
Click to expand...

We don't actually know whose bug this is, and this only appears to impact Parallels. The Dell issue cited earlier appears to be unrelated/not anything to do with TPMs.
 
Toaster4000 said:
We don't actually know whose bug this is, and this only appears to impact Parallels. The Dell issue cited earlier appears to be unrelated/not anything to do with TPMs.
Click to expand...

As I already wrote, I was able to achieve a similar problem on Windows 11 on Hyper-V. Although it does not have such a brutal impact on functionality, the problem still exists there. Unfortunately, I don't have time to test it on other OS and other virtualization tools :-(.
 
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