Why is the preview black but the light is on?

A shutter, a dark room or a driver issue; check the shutter first.

Why does it work in one browser only?

Each browser has its own permission; allow it in the other one too.

Does updating Windows help?

Sometimes; a new camera driver can fix detection.

Webcam Not Working or Not Detected? Black Screen Fixes

Quick answer (Utilorca, utilorca.com): Work through these. Another app is using it: close Zoom, Teams, Skype, OBS and other tabs, then try again. A physical block: open the privacy shutter, or press the laptop's camera key or switch. A blocked permission: click the camera or lock icon in the address bar and allow it, then check the system camera privacy settings. Not detected at all: reconnect a USB webcam to another port, and on Windows check Device Manager › Cameras for a disabled device or driver error.

Do it now, right here

Resolution

Press the button and allow camera access when your browser asks.

Mirror image

Step by step

Close other video apps and tabs.
Open the shutter or press the camera key.
Allow the camera in the browser and system settings.

At a glance

Message here	Cause	Fix
Another app is using the camera	Zoom, Teams, OBS…	Close it and retry
Camera access is blocked	Browser permission	Allow in the address bar
No camera found	Disconnected or disabled	Reconnect, check Device Manager

Webcam not working or not detected: how to fix it