MIDI input disappears after the computer sleeps

Your MIDI keyboard or controller worked before you closed the laptop, but the browser stopped receiving notes after wake. The device may have disconnected, or the browser may still be holding an old connection that did not recover from sleep.

Test the device outside your music app first. The MIDI Test can show whether your keyboard, knobs, pedals, and other controls send messages to the browser.

Check MIDI input after waking the computer

1. Open the MIDI Test in Chrome or Edge. MIDI Test does not work in Safari. If you need more detail about that limit, see why browser MIDI testing does not work in Safari.
2. Allow MIDI access if the browser asks. If no prompt appears, check the site's permissions in the browser's address-bar controls.
3. Choose your MIDI device if the test offers a device list. Press a few keys, then move a knob or press a pedal. Look for incoming MIDI messages or a response in the relevant control view.
4. Put the computer to sleep, wake it, and repeat the same actions without closing the test page. Note whether the device is still listed and whether new messages appear.
5. If input is still missing, unplug and reconnect the controller, or disconnect and reconnect it in Bluetooth settings. Reload the test page and check again.

For a useful comparison, test once before sleep and once after waking. A page that was already open during sleep may behave differently from a newly opened page, so try both before changing system settings.

What the result means

The device is listed and messages return after reconnecting

The controller and browser can communicate again. Sleep likely interrupted the connection, and reconnecting made the computer or browser discover the device afresh. If this happens repeatedly, use the fixes below to reduce disconnects.

The device is listed, but pressing controls sends nothing

The browser can see a MIDI device, but it is not receiving events from it. Check the controller's power, cable, selected output or operating mode, and any device-specific connection software. If the same controls work before sleep but not after it, the connection may be stuck even though the device name remains visible.

The device is missing from the list

The browser does not currently have a usable MIDI connection. Check whether the operating system still detects the device. If it is absent there too, the issue is below the browser, such as a USB or Bluetooth connection that did not resume.

Input works in a new page but not the old one

The computer reconnected the device, but the original page did not recover its MIDI session. Reload the page after waking, then grant access again if asked. If this only happens in one browser, update it or use another supported browser.

The test receives input, but your music app does not

The device and browser are working. The music app may have retained its own stale connection, selected a different MIDI input, or disabled input after sleep. Reconnect or restart that app, then confirm that the correct controller is enabled in its MIDI settings.

How to fix it

1. Reconnect the controller. Unplug a USB controller, wait a few seconds, then plug it back in. For a Bluetooth MIDI device, disconnect and reconnect it in Settings › Bluetooth & devices › Devices on Windows 11, or System Settings › Bluetooth on macOS.
2. Reload the browser page. A page left open during sleep may not refresh its connection when the computer wakes. Reload the test or close and reopen the tab, then check for a MIDI access prompt.
3. Check browser permission. Open the site's controls beside the address bar and make sure MIDI access is allowed if that permission is shown. You can also try a new tab. A permission change may not take effect in a page that was already open.
4. Check whether the operating system sees the device. On Windows 11, open Device Manager from Start and look for the controller under the relevant USB or sound device categories. On macOS, open Audio MIDI Setup and view the MIDI devices. If it is missing there, reconnect it before troubleshooting the browser.
5. Try another port or cable. Connect the controller directly to the computer rather than through a hub or dock. If it works on a different port, the hub, cable, or port may be losing power or failing to reconnect after sleep.
6. Check USB power management on Windows. In Device Manager, open the properties of the USB hub the controller uses, if available, and check its Power Management tab. If Allow the computer to turn off this device to save power is selected, try clearing it, then restart and retest. The tab is not available on every device.
7. Restart the computer and update device software. Restarting clears a connection the operating system has not recovered. If the problem returns, install current operating system updates and any controller driver or firmware update provided for your device.

When it's the hardware or connection

Test the controller on another computer if possible, and try a different data-capable USB cable or port. If it repeatedly disappears after sleep on more than one computer, or disconnects when you gently move the cable, the cable or controller may be faulty. A Bluetooth controller that drops on multiple devices may have a weak battery or a hardware problem. Check its warranty before paying for repair.

Why sleep can leave a stale MIDI connection

Sleep reduces power to parts of the computer. When it wakes, the operating system has to restore the USB or Bluetooth connection, and the browser has to update its list of MIDI devices. Those steps do not always happen at the same time. The device may be available again to the computer while an already-open browser page still holds an outdated connection.

The MIDI Test checks MIDI messages in the browser, not the sound produced by a synthesizer. If notes appear there but you hear no audio, troubleshoot the instrument or audio output separately.