Logitech C670i webcam stopped working starting with Big Sur

Any web application (Zoom, Photobooth, etc) not only fails with the external Logitech webcam connected, but the built-in FaceTime camera does not work with the webcam connected. The image flickers and then stops working completely until I disconnect the Logitech camera.

Troubleshooting:

• The external camera works fine with non macOS devices.

• When connecting the device, I can see it detected as a USB device.

• Tried different USB ports, and external hubs with same results.

What can I try next?

Solution 1:

After Big Sur upgrade my Logitech Streamcam stopped working too, but only when connected via USB-A adapter (even though it worked just fine in older MacOS versions). It does work fine in Big Sur when I use the Type-C connection though. Weird...

In general, I see a lot of people complaining about BigSur/Logitech issues, no staight-forward solution yet but some people indicated that installing Logi Options+ Beta solved their problems. You might as well give it a try and let us know the result =)