Why MIDI Recorder Says "No MIDI Devices Detected" or "This Browser Doesn't Support MIDI Access"

Updated

MIDI Recorder shows "No MIDI devices detected" when the browser can reach the Web MIDI API but finds no connected device, and "This browser doesn't support MIDI access" when the browser can't reach the API at all. The first is usually a hardware or connection problem; the second is almost always a browser problem. Fix the browser case by switching to Chrome or installing the Jazz-Soft Web MIDI API extension, and fix the device case by checking the physical connection before anything else.

What each message actually means

The two errors come from different points in the startup sequence, so they point to different causes.

Message What it means First thing to try
"This browser doesn't support MIDI access" The browser has no Web MIDI API available, so the app never gets far enough to look for devices Use Chrome, or install the Jazz-Soft Web MIDI API extension
"No MIDI devices detected" The API is available, but no MIDI input device is visible to the browser Confirm the keyboard is plugged in and powered on, then refresh
"Failed to get MIDI access" The API exists but the request for access did not succeed Refresh the page, then check browser permissions

If you see the "MIDI devices: Loading..." line stuck before either message, the app is still waiting on the browser's device list — the same fixes below apply.

Fixing "This browser doesn't support MIDI access"

This message means the browser itself can't provide MIDI access. The page's own guidance is to try Chrome, or for other browsers, install the Jazz-Soft Web MIDI API extension.

  1. Open the page in Chrome first. This is the shortest path, since Chrome exposes the Web MIDI API natively.
  2. If you want to stay in another browser, install the Jazz-Soft Web MIDI API extension, then reload the page.
  3. After either change, reload MIDI Recorder and check whether the "MIDI devices" line resolves to a device name instead of the error.

Note that the app requires JavaScript to run at all. If JavaScript is disabled or blocked, you'll see the "This app requires JavaScript" notice rather than a MIDI-specific error — enable JavaScript before troubleshooting MIDI.

Fixing "No MIDI devices detected"

Here the browser is working; it just can't see a keyboard. Work through these in order, since each step is cheaper than the next.

  1. Check the physical connection. Make sure the keyboard is plugged into your computer and turned on. A keyboard that is connected but powered off will not appear.
  2. Refresh the page. The device list is read when the page loads, so a device connected afterward may not show up until you reload.
  3. Unplug and plug the device back in. This forces the operating system to re-enumerate the device, which often makes it visible to the browser again.
  4. Restart your computer. This is the last resort in the app's own guidance, and it clears cases where the device is stuck at the system level.

If the device still doesn't appear after all four steps, the problem is likely outside the browser — for example, a driver or cable issue — rather than something MIDI Recorder can fix.

Verifying it worked

Once a device is recognized, the "MIDI devices" line stops showing "Loading..." and "No MIDI devices detected" and instead lists your connected device. From there:

  • Play a few notes on the keyboard. The app's demo function lets you confirm input is arriving without recording anything permanent.
  • Use Record to capture notes, then Stop when finished.
  • Use Export → Save MIDI File to download the result. If no notes were captured, the export shows "No notes recorded" — a quick signal that input never reached the app.

If you recorded something by mistake, Clear removes it, and Undo reverses the last action. Recover Recordings restores earlier takes; when there's nothing left to restore it reports "No more recordings to recover."

Common sticking points

  • Assuming the browser is fine because it's modern. Support for the Web MIDI API varies by browser, so a current browser can still show the "doesn't support MIDI access" message. The app's own recommendation is Chrome or the Jazz-Soft extension.
  • Skipping the power check. "Plugged in" and "turned on" are separate conditions, and a powered-off keyboard produces the same "No MIDI devices detected" message as an unplugged one.
  • Not refreshing after connecting. Connecting a keyboard while the page is already open often requires a reload before it appears.
  • Confusing the two errors. If you see the support message, no amount of replugging will help — change the browser or add the extension first.