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Recent Updates May Block RDP Access to Hyper-V VMs


Here’s an interesting mystery. In the wake of recent Win10 Updates — most notably KB4512941, KB4512508 and KB4515384 — some users have reporting vexing issues with using RDP to access Hyper-V VMs. The symptoms run in a sequence like this:

– Updates get applied
– First subsequent use of RDP into VM works just fine
– Host or client PC sleeps, or user terminates RDP session
– User is subsequently unable to access Hyper-V VM using RDP

The only workaround that seems to restore access is — you guessed it — to shut down and then restart the Hyper-V VM. That turns the next RDP attempt into another “first use after boot” so it works just that one time once again. This is hardly a desirable state of affairs.

In a recent TenForums thread “After August update Hyper-V Win10VM crashes when connecting via RDP” a number of interesting info items come up. First, only some Windows 10 users are affected by this problem. Second, other unaffected users have so far been unable to reproduce the problem on their test machines and VMs. Third, RDP issues have yet to make their way onto the Windows 10 1903 Known Issues list.

Affected? Please post to Feedback Hub!!

Poking around on the Feedback Hub, I really don’t see this issue reported. To me, that says if you are affected, please post (or upvote) a thread on the hub. I humbly suggest “RDP to Hyper-V VM works on first try, won’t connect afterward” as a common title everybody can recognize and use. I don’t have the issue myself, or I already would have reported it.

But lately, we’ve seen profound evidence that MS is adding items to the Issues list more quickly than ever — and fixing them pretty quickly, too. I discussed this right here on Win10.Guru in a September 11 post entitled “Patch Tuesday KB4515384 Resolves KB4512941 Search Issues.” The inestimable Ed Bott produced a more comprehensive and nuanced analysis along the same lines at ZDnet today: Windows 10: Has Microsoft cleaned up its update mess? (Spoiler: Maybe).

I firmly believe that MS will fix this problem if enough people who’ve got it provide input to the feedback hub and/or upvote such input. This is the way the system is supposed to work, so please help keep it working! You might also find this TechNet Forums item of interest, even though it goes back to Build 15063 (a 1703 version): Cannot reconnect to Hyper-V VM once initial RDP connection is closed. Apparently this is not the first time this kind of thing has happened.

Very interesting! I’m curious to see if this will make the Known Issues list. If so, I’m even more curious to see how long it takes for a fix to show up.

[Note added September 19] I couldn’t find this TenForums thread when I went looking for it yesterday, but here it is now (a bit late, but hopefully welcome). Entitled After August update Hyper-v Win10VM crashes when connecting via RDP, it spells out several potential workarounds that include (a) various registry hacks and (b) disabling WDDM (see thread #22). I don’t have the issue so I can’t vouch for either (or all) of the suggested fixes. Trial and error time, I guess!

Author: Ed Tittel

Ed Tittel is a 30-plus-year computer industry veteran. He’s a Princeton and multiple University of Texas graduate who’s worked in IT since 1981 when he started his first programming job. Over the past three decades he’s also worked as a manager, technical evangelist, consultant, trainer, and an expert witness. See his professional bio for all the details.

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