This is a post to assist customers with known bigger issues or workarounds, in the interest of remaining transparent on this project and unblocking customers and companies. Please see links below to our Discord server for further discussion and workarounds.

Updated March 17, 2026.

Main Windows MIDI Services Announcement blog post

The issues and workarounds here apply only to the new Windows MIDI Services rollout in Windows 11 retail 24h2 and 25h2. This does not apply to older versions of Windows. Insider builds get different releases on a different schedule so this information may or may not apply to a Windows Insider Canary/Dev/Beta release.

We performed multiple years of testing with customers, partners, and our own equipment over the development cycle for Windows MIDI Services, but some bugs have made it through, as is known to happen with software development. We’re working on them in priority order, but I wanted to ensure the most impactful ones have more detail here.

Full issue list and updates for bugs may be found on our GitHub Repo

For support, join our Discord Server

Info: How do I know if the new Windows MIDI Services Stack is enabled?

Windows MIDI Services is part of a Phased Rollout, and that applies to most of the fixes after the initial January release. This means that after you install the KB which contains the Windows MIDI Services binaries, you will get the new feature enabled at some point in the next 30 days. Who gets enabled depends on the algorithms that control the rollout phases.

To see if your PC has the new Windows MIDI Services feature enabled, go to https://aka.ms/midi and download the checker tool there. It will be up until the next SDK release, where it will be included as part of the SDK and Tools package. Run this checker and pay attention to the output. It will tell you if the new stack has been enabled on your PC as part of the phased rollout. If it says it has not been enabled, then you are still running the older Windows MIDI stack, and any issues are unrelated to this release of Windows MIDI Services.

Info: MIDI unreliable on Insider builds.

Windows Insider Dev/Beta especially have an older partial rollout where only 50% of users will ever receive the new bits. Canary is behind as well. Please use retail 24h2 or 25h2 if you want to use the new Windows MIDI Services.

Issues

Issue: inMusic-branded companies’ drivers lock up the MIDI Service

Status: Open issue. inMusic is working on it.

This causes apps like Cubase and other DAWs to hang when initializing MIDI, requiring a reboot to recover. In general, it can cause all MIDI devices to appear unresponsive.

This impacts nearly all the inMusic drivers including the m-audio drivers, AKAI drivers, RANE, Denon DJ, and others, regardless of device. Most of the newer MIDI devices are class-compliant and so work quite well if you do not download and install the vendor-provided driver. For example, the popular AKAI MPK mkIV works well with our in-box driver, and if you use the latest release candidate of the tools, you can rename it to match the names provided by the vendor driver.

Update March 17, 2026: We validated earlier this month that this driver crashes apps on Windows without Windows MIDI Services installed, and inMusic has confirmed. But it wasn’t always obvious to the user that the MIDI connection had crashed, and it was possible to fix it by unplugging and replugging the device. The driver itself has an issue we cannot easily work around in the MIDI stack. We’ll work with inMusic to get this resolved, but it may take some time.

The service lockup happens when we try to close the driver. Other third-party drivers are fine, but these drivers (new and old, regardless of device) all lock up when asked to stop.

Again, we’re working with inMusic on this, and they are being very helpful and responsive.

Workaround 1:

If you have one of the more recent devices which is class compliant (it works on other operating systems without a vendor driver, this includes some of the older devices) then unplug the device, completely uninstall the M-Audio/Akai/etc. driver from Windows, and then reboot and plug it back in. At that point, if the uninstall worked correctly, it will use our in-box MIDI 1.0 driver. We have instructions and can help you with this on our Discord server.

Workaround 2:

For combined audio/MIDI devices where you cannot use our class driver, different types of drivers like the AKAI Network driver, and older non-class-compliant devices, join our Discord Server and look in the #start-here channel for instructions.

Bug: Dynamic ports (loopMIDI, loopBE, virtualTE / teVirtualMIDI / rtpMIDI) are not always visible.

Status: Preview Fix Available, in-Windows fix coming end of April

Problem: Third-party drivers which dynamically create MIDI ports in Windows do not work as before. Unless the ports were created before the service was started, they are not visible. Additionally, if you have more than 16 loopback ports defined in either loopBE or loopMIDI, only 16 will be available, and the names may be messed up.

The primary issue is the order in which the various components (the third-party product, the MIDI Service, the app) start up. But it can be difficult to align that in a way which functions in the way you want.

Github Issue 835

Github issue 852

Known to affect:

• loopMIDI
• loopBE / loopBE30
• teVirtualMIDI (used by loopMIDI and rtpMIDI as well)
• Sonic Core software-defined MIDI ports
• te rtpMIDI
• IP MIDI

Possibly impacts

• SSL 360 link
• MPC Live III
• Possibly other AKAI apps

The problem is that the devices create the ports after midisrv has already started, and we don’t currently detect new ports added to an existing device.

Workaround 1: Install the KSA Preview Transport from our Discord server

The Discord Server has an #early-preview-releases channel. In that is the updated KSA Transport which no longer requires restarting the service, and has support for endpoints added after the service has started, as well as support for more 16 virtual ports. This is what will ship in Windows at the end of April, available as an unsigned preview here.

This does require turning on developer mode to install. Developer Mode doesn’t do much other than tell us that you are ok with loading an unsigned MIDI service plugin. More information about Developer Mode here..

Workaround 2: For basic loopback, use our in-box MIDI 1.0 Basic Loopback Preview

We have a preview of MIDI 1.0 basic loopback support for Windows MIDI Services on GitHub here. This doesn’t require any third-party drivers, and is native to the new MIDI Services. You can even name the ports exactly the same as you were with third-party products, so your scripts do not need to change.

Just follow the installations instructions in the release post. We will ship this in Windows later this year. There are no practical limits to the number of ports you can create, and they are natively implemented in the MIDI Service, so super fast.

This does require turning on developer mode to install. Developer Mode doesn’t do much other than tell us that you are ok with loading an unsigned MIDI service plugin. More information about Developer Mode here..

You will need both the Service Plugin Preview and the MIDI App SDK & Tools as descripted in the release information.

Bug: WinRT MIDI 1.0 Timestamps are in the future, so no messages received.

Status: Preview Fix available. In-Windows fix coming in April/May

This impacts Cakewalk Sonar and Steinberg Cubase when set to use WinRT MIDI, and also djay pro. The fix will be in Windows in a few months. In the meantime, a patch is available here.

WinRT MIDI 1.0 Timestamp Fix

Github Issue 847

Issue: Some apps may connect to the wrong device if you have multiple identical MIDI devices with the same names

Status: Preview fix available. In-Windows fix coming at the end of April.

The old WinMM API doesn’t really have any way for apps to find ports other than the name, and the new code doesn’t go out of its way to ensure there are no duplicate port names in the system. This is something we’re working to fix.

Workaround 1

If the app allows it (like Cubase), select the option to use the WinRT MIDI API instead of the original WinMM/”Windows MIDI” API

Workaround 2

Install the KSA preview as described in the loopMIDI issue here. The KSA preview also handles ensuring unique names.

GitHub Issue 861

Bug: Apps using the WinMM MIDI 1.0 API may not see newly plugged-in devices.

Status: In-Windows fix started rolling out at the end of February, and will be available on all customer PCs by end of March

If you connect or power on a USB MIDI device after you’ve already started an app using the older WinMM MIDI 1.0 API, the device may not be visible.

This can also be true of browser-based MIDI apps.

The fix for this started releasing to the public in the February 2026 update the week of February 23. It takes up to 30 days for everyone to get it enabled. Ensure Windows is up-to-date

GitHub Issue 783

Workaround 1: Plug in your MIDI device early

Plug in the MIDI device and ensure it has fully booted up before starting the app.

Workaround 2: Use more than one MIDI device

If you plug in multiple MIDI devices, apps will receive the notification that new devices have been added. The problem was only happening when the MIDI device was the sole connected and powered on MIDI device

Bug: Apps using the WinMM MIDI 1.0 API may crash if you disconnect or power down a plugged-in device

Status: In-Windows fix started rolling out at the end of February, and will be available on all customer PCs by end of March

If you disconnect, power down, or otherwise restart a USB MIDI device while an app is using it, that application may crash, depending upon how it has opened the device. This may also require a reboot to clear, depending upon the application.

The fix for this started releasing to the public in the February 2026 update the week of February 23. It takes up to 30 days for everyone to get it enabled. Ensure Windows is up-to-date

GitHub Issue 831

Workaround:

Wait until the app has exited before unplugging or powering down a device. This also applies to dynamically-created devices that are not physical USB devices.

Issue: VirtualDJ Not able to communicate with controller

Status: Fixed by VirtualDJ, Windows workaround going out at the end of March

We have worked with VirtualDJ on this, and would like to thank them for their cooperation and quick response.

The new MIDI stack is much faster than the old one, so we’re finding that some apps are running into errors that they hadn’t previously run into. In the case of VirtualDJ, this results in the UI freezing up.

We’ll have a broader fix in Windows. In the meantime, VirtualDJ have released their Build 9005 with a fix for this. You can download it from their main download page, or let your copy of VirtualDJ update itself.

GitHub Issue 843

Issue: Spin Rhythm XD Appears to lock up if MIDI is enabled

Status: Fixed by Spin Rhythm

This is the first app we’ve found which broke with the new multi-client support. As a result, it just keeps sending messages to all the ports because none of them ever fail.

Multi-client is the key feature in the new stack, and the #1 request from customers. We do not plan to disable this in any way.

Fix

The Spin Rhythm XD team quickly put out a patch for the game. Please see their Discord server for details.

General Issues

Issue: Korg USB devices using a .DRV winmm-style driver are not recognized

Status: By design.

The new Windows MIDI Services stack does not load the older-style .DRV WinMM drivers and this may cause the device to not appear, or in some cases, apps using MIDI to take a very long time to list devices, appearing to hang. Luckily, there’s very little need for those old-style drivers anymore as the new stack is fully multi-client and supports class-compliant USB MIDI devices.

There is no plan to change this behavior.

Fix

Completely uninstall and remove the driver. This can be tricky with the Korg drivers in-particular because they tend to cause issues in the registry. We have complete instructions on our Discord Server in the #workarounds-and-instructions channel.

These are the only required registry entries for Windows MIDI Services.

Issue: Korg devices using the Korg BLE driver may not show up.

Status: Instructions below on how to fix this.

Instructions

We will eventually have a first-class BLE MIDI 1.0 transport in Windows MIDI Services. Today, you can continue to use the Korg driver for BLE MIDI (we do not recommend using their drivers for USB MIDI as those conflict with the USB MIDI Support in the MIDI Service).

Because the Korg BLE MIDI driver is an older style WinMM driver, it needs to be loaded in addition to the new Windows MIDI Services wdmaud2.drv. Because of this, it will not appear in any of the tools provided with Windows MIDI Services and will not be multi-client.

After installing the latest Korg BLE MIDI driver, the registry should have the following entries

Open regedit and paste this location into the address bar at the top of the app

Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Drivers32

You should see these entries:

• midi REG_SZ wdmaud.drv
• midi1 REG_SZ wdmaud2.drv
• midi2 REG_SZ korgbm64.drv

Here’s the explanation of what those entries do

• wdmaud.drv provides the in-box MIDI 1.0 synthesizer
• wdmaud2.drv provides the Windows MIDI Service and all USB devices, loopbacks, and more.
• korgbm64.drv provides the Korg BLE MIDI 1.0 devices

With those entries in place, all your devices should be working. There should be no other Korg .drv files in that list. Also note that “midi0” is not a valid entry. That entry needs to be named “midi”.

How to uninstall the update if needed

The KBs are all over 10 days old now, so uninstallation is typically not an option. However, we have additional information on our Discord Server in the #start-here section for those who are blocked by the issues here.

Other Important Notes

Do not use the Korg Driver Uninstaller or any other tool which works to change the ordering of midi…midi9 entries in the registry. Windows MIDI Services requires only that midi is set to wdmaud.drv and midi1 is set to wdmaud2.drv. If those two entries are not present, Windows MIDI Services will not work on your system. The SDK runtime and tools includes a tool midifixreg which will ensure these two settings exist, in case you’ve already run one of these tools on your system.

How to File Bugs or Report Issues

Please do not comment on this post with issues/bugs/questions.

Questions/Discussion, and for customers without access to GitHub, issue reporting: https://aka.ms/mididiscord

Developers and anyone else with access to GitHub can file issues here: https://aka.ms/midirepoissues