What `NotReadableError: Could Not Start Video Source` Means (And Fixes)

This error sits at a meaningfully different point in the process than a permission or missing-device error: the browser has already confirmed both that a camera exists and that it has permission to use it, and the request still fails specifically at the hardware access step. This narrows down the likely cause considerably compared to a more generic failure.

Most cameras only support one active connection at a time by design — this is a hardware and driver-level limitation, not a software restriction any single app can work around. When a second application requests the same camera while another already holds it, the operating system denies the new request rather than somehow sharing the stream between both.

Less commonly, this error can also indicate a genuine driver problem, particularly right after a system update, or a physical connection issue with an external USB camera — a loose cable or a marginal USB port that provides just enough connection for the device to be detected, but not enough for a stable data stream.

Step 1: Close every other application that might be using the camera

Including other browser tabs, video-calling software running in the background, and system tray or menu bar apps.

Step 2: Check your OS task manager

(Windows: Ctrl+Shift+Esc; Mac: Activity Monitor) for anything unexpected still running that might hold the lock.

Step 3: Restart your browser fully

If closing other apps doesn't resolve it, since a crashed tab from earlier can occasionally leave a stale lock behind.

Step 4: For an external USB camera, try a different USB port

And inspect the cable for damage, ruling out a marginal physical connection.

Step 5: Restart your computer

As a reliable fallback if the error persists, since this clears virtually any stuck lock regardless of its original cause. ↑ Test with the widget above afterward.

How do I reset the Windows Camera app itself?

Go to Settings → Apps → Installed apps, find Camera, open its three-dot menu, and choose Advanced options → Reset. This clears the built-in Camera app’s own cache and settings without uninstalling it, which can fix a stuck, frozen, or permanently black preview even when the underlying device and driver are both working correctly. It only resets that one app — not your camera driver, and not other applications that use the camera.

Could my antivirus be silently blocking my camera?

Many third-party security suites — Bitdefender, Kaspersky, Norton, and ESET among others — include their own webcam-protection feature that runs independently of Windows’ own privacy settings. That means Windows can show camera access as fully permitted while the antivirus software blocks it anyway, at a layer Windows has no visibility into. Check the antivirus program’s own settings, usually under a Privacy, Webcam Protection, or similarly named section, and confirm your browser or conferencing app is on its allow-list.

How do I re-enable my camera in Device Manager if it's disabled?

Right-click the Start button → Device Manager, expand Cameras or Imaging devices, and look for a greyed-out icon or a small down-arrow badge. Right-click that entry and choose Enable device. This is a different action from updating a driver — a disabled device won’t respond to any other fix until it’s explicitly re-enabled here first, so it’s worth checking before assuming the problem is a driver or a permission.

Is Windows' own camera privacy toggle blocking access, separately from anything else?

Windows keeps a system-level camera permission at Settings → Privacy & security → Camera, completely separate from Device Manager, the Camera app, and any antivirus software. This one screen has a master Camera access switch plus a per-app list beneath it — both need to be on. It’s worth checking directly, since a camera can show as fully enabled and working in Device Manager while this toggle silently blocks every app from reaching it.