I was experimenting with RDS Shadowing, which is something I've rarely used up until this point, and noticed it just doesn't work on my Windows 10 boxes. It's a super cool feature, where admins can peak in on desktop sessions and provide remote assistance, just like you could with a third party screen sharing app, but all within the well established Remote Desktop Protocol. I want to add this to RD Tabs for help desk users so they can remotely assist in addition to remotely manage.
I did some searching and saw that the Meltdown/Spectre OS patch from January seems to have broken shadowing. A later cumulative update fixed it, but then the cumulative updates after that one don't contain the fix. It's kind of a mess. It may be more complicated than that. Now, I can't say for sure, I don't have good logs, but I'm pretty sure I applied all the cumulatives in order each month and yet I'm still exhibiting this issue in my test lab and live systems I manage.
I was going to add shadowing support to RD Tabs 3.1, the next major release, but now I think I'm going to hold off on that for a little while until the dust settles. I can't even get it to work with mstsc.exe with Windows 10 (oddly, my Server 2016 boxes with basically the same patches work fine), so it would make debugging adding the feature very difficult.
Bugs happen, but this response seems like a strange mess right now. I'll have to see if I am able to open a support case with MS to get to the bottom of it.
For those interested, basically what happens is when you try to shadow a session, you get an error that just say Shadow Error / Unspecified error. Great error!
Here's a thread talking about it: https://community.spiceworks.com/topic/1295608-windows-2012r2-rds-shadowing-unspecified-error
There are some who apparently no longer have the issue if they installed the (now old) cumulative update. I am guessing I must have some how missed it, but I don't see how, it was a normal cumulative that would have gone through my normal patch process. *shrug* I do know I'm not alone, I see there are others that still have the issue. And it seems with build 1709, it may never have been even patched (I'm seeing conflicting messages).
Well, anyway, if anybody was looking forward to this RD Tabs feature, you'll have to wait a little longer. Hopefully Microsoft will get this all fixed soon.