@Derek For what it’s worth, I was in a similar situation: I could get things working right with the KSA, but removing it (or turning off Developer Mode) killed certain MIDI functions. The wrinkle is, the new Windows MIDI stack is now a released item. Sooner or later MS is essentially going to force the update on your PC, unless you continue to refuse updates indefinitely and live with the compatibility and security risks. I am of the opinion that we are essentially near or at that point.
The problem with the update is, the KSA is invisible as far as Windows Update is concerned, so there is no revision trail. Removing it after any other updates or patches may result in issue. When I removed the KSA and installed the latest (5-2026 and 6-2026) updates, something in the chain broke.
Fortunately, Windows has a built-in recovery process that worked nicely for me. It’s supposed to update a PC to the latest version while maintaining all of the options, apps, etc. – and it appears to work. If you or anyone else wants to follow in my footsteps, here is the exact process I took.
I installed the KSA right around the end of February, so my working baseline is probably the 2-2026 version of Windows 11.
I turned off updates on or about 15-Mar. (In retrospect, I should have stopped updating when the KSA was first loaded.)
On 8-Jun, I made backups of my PC and Cantabile. I removed the KSA, then turned on Windows updates again. I installed the recommended 5-2026 Windows 11 update. My MIDI system was completely broken, as described in my OP.
Checking Windows Update again, I saw that there was a newer update (that didn’t appear before installing 5-2026) called “6-2026 Preview” or something similar. I installed this update. My MIDI system was still broken.
I checked Windows Update again and was told that my PC was up to date.
I ran the Settings > System > Recovery > Fix problems using Windows Update option. This downloads yet another ‘update’ and installs the software. It reboots the PC several times during the process.
When it was finished, a) all MIDI ports were functional, including loopMIDI and rtpMIDI entries; b) Windows Update reported that my PC was fully up-to-date; and c) all of my apps, UI settings, etc. were set up as before.
There were a couple of minor issues with previously installed and functioning products that were easy to fix. (ex: Cantabile asked me to provide my license credentials again.)
I haven’t tried setting things up without loopMIDI, nor have I investigated whether MS has USB drivers for my keyboards that are ‘better’ than the ones I already had installed.
Thanks for the detailed info. I will go through the steps you outline after a rehearsal on Saturday to see if that resolves the issue. In the meantime I have a working system, so no more updates until after the rehearsal…
I’ll give it a go after that and report back
PS: I forgot to say that I always removed the KSA before letting Windows update
Just to be clear, in MY case, I installed the KSA, then didn’t turn off Windows Update for a few more days. (This may not reflect your situation.) I’m theorizing that there was at least one additional change made in Windows 11 on my PC between the time that I installed the KSA and I stopped all future updates. If this is the case, then when I uninstalled the KSA it probably didn’t put my system back “just like it was” – at least, in the case of MIDI – and the newest updates didn’t fix that problem. I had to run the additional recovery steps, which re-initialized the MIDI stack along the way.
If you were more meticulous than me, you may find that simply running the latest approved Windows updates works fine, because MS claims that the 6-2026 updates for all currently-supported Windows variants contain a functional MIDI 2.0/1.0+ system. But it would also seem that the recovery fix can correct a certain degree of synchronization issues. So, before I would immediately jump back to a backup version of Windows it seems worth running the Fix problems using Windows Update step.
Just for completeness, I had forgotten to read my own notes about the manual uninstall steps needed as simply uninstalling the KSA via Add or Remove Programs does not fully remove the KSA, or more to the point it leaves the MIDI stack in a non functioning state… hence the problems I was seeing.
To completely revert back from the KSA to the release MIDI stack you also have to do the following from an administrator CMD console:
regsvr32 %windir%\System32\Midi2.KSAggregateTransport.dll
regsvr32 %windir%\System32\Midi2.BS2UMPTransform.dll
net stop midisrv
net start midisrv
RTFM…
I have now fully removed the KSA and backed out of developer mode on my DAWPC, GIGPC and Video PC, and it all seems to be working fine now (including them communicating via RTPMIDI).
So all looks good now and no interim fixes needed.
I have been following this thread, but, until yesterday, I hadn’t been affected. Sharing my experience. Which wasn’t too bad.
Update happened about an hour before ptactice when I powered up for some last minute cramming. I was expecting major issues, but the only problem I had was with StreamDeck+. I’m using mixture of Brad’s direct button interface and Elgato’s midi app for knobs. Buttons were still working. Knobs dead.
A little digging today indicated the problem was loop midi. Specifically a driver error. There was some help on the website for the Elgato midi app. I killed loop midi and installed the windows midi services app, added a loop port named StreamDeck (same name I had in loop midi) and all is well. The MS app is a little confusing as it implies that you are adding midi 2.0 loopback. But it worked.
My other virtual midi devices (Divisimate/bome) worked out of the box with the new services.
While grabbing the midi services app, I noticed that there is a developer version of Bluetooth midi up there. Has anyone tried that? I may give it a try, but I have a gig Sunday. I won’t push my luck before that.
Thanks for bringing up the Bluetooth midi question. I use bridging apps and would love to try out the new developers midi app if it’s stable enough for live use.