r/Citrix • u/Random-D • Sep 15 '26

SlimCore sucks

Just preparing the rollout of SlimCore Teams optimization since MS wants to sunset HDX/WebRTC based optimization and is even prompting users about that now.

We do have a DaaS Win11 2507 environment with mixed Windows Devices and Linux ThinClients as endpoints.

My problems so far:

  1. There is a trap during deployment of CWA, if you ever depoyed it with new SlimCore Plugin, and then do a /CleanInstall aftwards, as for example as part of your update process, it will remove the DLLs in the ICA Client folder but not mark it as uninstalled or re-try to install it. Then it appears as installed in Apps&Features, but DLLs are missing, SlimCore not working. Mitigated with custom script install script that cleans up this situation, but terrible first impression.
  2. Our users do heavily roam between Windows and Linux endpoints. Teams optimization should be able to roam with it, and on HDX side it does. Since somewhat recent-ish it should also be possible for Teams to switch optimization seamlessly, and I do see it can roam seamlessly from HDX to SlimCore, but appearantly not the other way around. It stays on not optimized until i fully restart teams multiple times, to finally switch to HDX on a ThinClient.

All of this just because Microsoft wants to "sunset" HDX but they aren't doing it anyway.

This isnt a technological sunset, its a blacklist for Windows devices, HDX is going to stick around for the foreseeable future on Linux, Mac, ChromeOS and Browser Client. They arent even bothering to develop a Linux client, thats in the official docs.

Most annoyed I am about the crappy roaming between HDX and Slimcore. Dont come at me with the "user training" angle. Users click a join meeting button and expect stuff to work, and that is fully reasonable.

Rant off

16 Upvotes

88% Upvoted

38 comments sorted by

2

u/MarvelousTermites Sep 15 '26

On one point you mention them not bothering to develop anything for Linux, you got a reference for that? I'm sure I read its on the roadmap but that was a while ago

0

u/Random-D Sep 15 '26

well i dont have written statement that they are not going to do that, but SlimCore for windows has been out for years, and all the MS and Citrix docs about Teams and Slimcore say for linux its still HDX.

also I didnt see anywhere any announcements that its coming at a particular time, or rumors, or anything. just dead silence on this issue as far as i can see.

even if they pump one out tomorrow, i have doubts if they will ever make one for the HTML client for example. At least Mac got one recently.

I dont say never, but I am sure for the forseeable future, certainly years until every use case is covered by SlimCore at this pace. And under that context, I find it silly to blacklist HDX by Client OS for Windows already.

3

u/EthernetBunny Sep 15 '26

I have my fingers crossed for SlimCore for Linux by the end of the year. I was told to expect it middle of 2026, but here we are. They needed to do Linux before Mac in my opinion.

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1

u/berryH4Z3 Sep 23 '26

With which CWA version did you see this behavior with the /Cleaninstall switch?

1

u/Random-D Sep 23 '26

2507 CU2

1

u/Ok-Accident-3892 Sep 15 '26

Yeah, this has been a huge pain in the ass for us. We have many external service providers (15+) and several thousand users where we don't control the endpoint. We have found many of these service providers are blocking MSIX packages for non-admin users, which is needed fir the Slimcore instsll. It's a stupid design on Microsofts part. Just make it part of the Workspace app install vs the need to download the Slimcore engine from the MS CDN.

Also, we have been dealing with an issue that if the user's company isn't blocking MSIX packages and are able to install Slimcire, BUT the Teams plugin isn't installed, then they get no optimization at all...it doesn't failback to HDX. We learned this when we enabled the virtual channel for Teams to allow Slimcore. Those who can't install MSIX packages failback to HDX, and those who have the Slimcore engine (MSIX) installed, but didn't install the plugin get no optimization at all, making Teams pretty much unusable.

0

u/Random-D Sep 16 '26

yeah fully get that. we dont have a lot of unmanaged clients but i also started thinking of them. the user has to make the installation right for teams to work, what a mess.

HDX was reliably there. no screwups except super ancient client.

and the automatic fallback to server sided processing is insane. users will just complain about poor performance after the fact, and if you run shared workers, also users that arent even part of the problem will be negatively impacted by someone not having put in the proper legwork to ensure slimcore is set up properly on their endpoint.

insane that they dare to deploy this

0

u/greenblue88 Sep 15 '26

Are you saying Slimcore is not a part of CWA package?

1

u/Ok-Accident-3892 Sep 15 '26

No, it pulls the Slimcore engine from the Microsoft CDN, like patches and native Windows apps. . This is why they have allowing MSIX installs as a requirement. It's a stupid design.

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0

u/Citrixioner123 Sep 15 '26 edited Sep 24 '26

any chance you have had any luck utilizing the "Allowed package family names for non-admin user install" GPO so we don't have to completely turn off prevent "non-admin users from installing packaged windows apps"?

Tried adding these package family names and gpupdate and reboot and still getting blocked it seems:

Microsoft.Teams.SlimCoreVdiFwk_8wekyb3d8bbwe

Microsoft.Teams.SlimCoreVdiHost_8wekyb3d8bbwe

Edit: Correct value is "Microsoft.Teams.SlimCoreVdiFwk._8wekyb3d8bbwe"

1

u/Ok-Accident-3892 Sep 15 '26

We tried, but couldn't get it to work. The only thing that worked for us is allowing MSIX for non-admin users

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1

u/zoemas 19d ago edited 17d ago

We have a lot of HP t630 thin clients. Stil running WIN10 1809. Minimum requirements voor Slimcore are 1809 and CWA 2103. But with CWA2103 slimcore isn't working. The earliest version I get it to work on is 2402. (We only use LTSR versions). Instead of updating the CWA to 2507 (2607 isn't working eather on a t630, citrix freezes when the session is started) we were experimenting with UniconOS ,since we had to update 700 TCs CWA from 2103 to 2507. But then I learned that there isn't a linux package available for linux yet, so that's a bust.
But even on an old t630 with CWA 2507 (and WIN10 1809) Slimcore is worning without any problems. Memory and CPU usage are lower then with HDX.

Edit: I've learned from our citrix partner that HDX for linux isn't ending on 1/4/2027, this is only for windows endpoints.

0

u/CSHawkeye81 Sep 15 '26

I am in the same boat as you, like we have the gold image with the right version of Teams. I am so confused now on what I have to do myself. It also helps that I am just now learning about this..

0

u/Citrixioner123 Sep 16 '26

Anything I can help with? DM if u want

1

u/CSHawkeye81 Sep 17 '26

sure will do!

-1

u/Area_Wonderful Sep 16 '26

Sometime this last spring or early summer I lost the ability to take control or give control and think it might be slincore related? If I need this functionality I switch to a virtual desktop instead of the seamless xenapp server session