[BUG]: Windows 11 KB5077181 (26200.7840) causes Hotone/Valeton USB MIDI device disconnect loop during firmware update, preventing transfer and leaving device stuck in bootloader mode

Windows Version

OS: Windows 11 (24H2 / 25H2), Update installed: KB5077181 (February 2026 security update), Occurs on multiple PCs (tested on two separate systems)

Service Installation Method

In-box In Insider Build

SDK version, if appropriate

No response

Location

Application using WinMM MIDI 1.0 (Classic API)

Type of bug

MIDI messages corrupted

Steps to reproduce

After installing Windows 11 security update KB5077181, USB MIDI devices become unstable during firmware update operations. When attempting to flash firmware, the device repeatedly disconnects and reconnects, preventing the update process from starting. This leaves the device stuck in bootloader/restore mode and unusable.

This issue appears to be related to recent changes in the Windows MIDI/USB stack and may be connected to known SysEx and device reconnection problems.

Device:

Valeton GP-200 (USB MIDI audio device with firmware update capability)

Steps to Reproduce:

Connect a USB MIDI device capable of firmware update to a Windows 11 system with KB5077181 installed
Place the device into firmware update / bootloader mode
Launch the vendor’s firmware update software
Begin firmware transfer

Actual Result:

The device screen flashes and immediately disconnects from Windows
Windows reconnects the device automatically
This disconnect/reconnect loop repeats continuously
Firmware transfer never begins
Device remains stuck on firmware update/restore screen and cannot exit

Expected behavior

Stable USB connection during firmware update
Firmware transfer initiates and completes successfully
Device exits bootloader mode normally

Additional notes

Troubleshooting Performed:

Tested on two different Windows 11 PCs with identical results
Tried multiple USB ports, including motherboard USB 2.0 ports
Tried multiple USB cables
Reinstalled vendor drivers and tested generic Windows USB audio driver
Disabled USB selective suspend
Attempted to stop Windows MIDI services
Tested multiple versions of the vendor firmware software
Attempted different boot/recovery modes on the device

None of the above steps resolved the issue.

The device works normally prior to installing KB5077181
The issue prevents any firmware recovery because the connection is unstable during bootloader mode
The manufacturer has indicated this may be caused by recent Windows MIDI/USB changes introduced in this update
This may be related to existing issues involving SysEx transmission failures and device reconnection instability

This issue can leave USB MIDI devices permanently stuck in firmware update mode, effectively rendering them unusable until access to a non-affected system is available.