Start with the simple checks. Change one thing at a time so you can tell which step helped.
Another app may be using the camera, permission may be denied or an external camera may be selected. First, note what changed recently and whether the same issue affects another device. This helps separate a device-specific fault from a wider network or service issue.
Troubleshooting steps
Check the basics
Quit other video apps and reopen the app where the camera fails. After each change, repeat the action that originally failed and give the device a moment to reconnect or refresh.
Review the settings
Review Camera privacy permission for that app in macOS settings. After each change, repeat the action that originally failed and give the device a moment to reconnect or refresh.
Test one change
Check the app’s own video source menu if you use an external camera. After each change, repeat the action that originally failed and give the device a moment to reconnect or refresh.
Confirm the result
Restart the Mac and install available app or system updates. After each change, repeat the action that originally failed and give the device a moment to reconnect or refresh.
Helpful note
Use only apps you trust when granting camera access, and revoke access when no longer needed.
When to get more help
If these checks do not resolve the issue, contact the relevant device maker, internet provider or app support team. Include the exact model, software version, any error message, what you have already tried and when the problem began. Avoid sharing passwords, verification codes or private account details in a public forum.
For equipment that is hot, damaged, wet or making unusual electrical sounds, stop using it and seek qualified support. Do not open power supplies, batteries or mains-powered equipment.
Settings and menu names vary by model and software version. Use the manufacturer's current instructions for device-specific steps, and back up important files before making changes that could remove data.