You clicked Capture screen, picked a window, and got back a black rectangle. Or nothing at all. Or the browser refused before you could pick anything. The frustrating part is that the fix is usually fast once you know which of three things went wrong: the permission got denied, the content is protected, or you shared the wrong surface.
Work through them in that order. Each has a distinct symptom, so you can usually tell within a second which one you are looking at.
Symptom: the browser never showed the share picker
If you clicked Capture screen and no dialog appeared asking you to choose a window or screen, the permission was blocked before it started. This is a browser-level or operating-system-level denial, not a problem with the page.
On macOS, the browser itself needs permission to record the screen. Open System Settings, go to Privacy and Security, then Screen Recording, and confirm your browser (Chrome or Edge) is toggled on. If you just turned it on, quit the browser fully and reopen it. macOS does not apply the change to a running browser.
Inside the browser, check the site permissions. If you clicked Block on an earlier prompt, the browser remembers it and will silently refuse. In Chrome, click the tune or lock icon to the left of the address bar, find the screen capture or camera permission, and set it back to Ask. Reload the tab and try again.
If the whole thing is happening on a locked-down work machine, the denial may be a policy you cannot change. The 'permission denied' when sharing your screen answer covers what to check when the block is coming from IT rather than a setting you own.
Symptom: the picker worked but the capture came back black
You saw the share dialog, picked a window, and the captured still is solid black or shows everything except one region. This is almost always protected content. Browsers and operating systems deliberately blank out anything covered by digital rights protection so it cannot be copied.
The usual culprits:
- A Netflix, Disney+, or other streaming video tab renders as a black box.
- Some banking and payment screens block capture on purpose.
- A few native apps mark their windows as protected, so sharing that specific window gives you black.
There is no setting that overrides this. It is working as designed. If you need to show what a protected video or window looks like, the practical move is to capture a different surface, or describe the issue in words on a free-floating comment instead of a screenshot. The can't capture a video or protected window answer explains exactly which content triggers this and what your options are.
Worth knowing: Cobalt Capture takes still frames, not video, so you are never trying to capture a playing movie in the first place. If you meant to record motion, that is a different tool entirely, and the difference between screen capture and screen recording matters for what you can send.
Symptom: the capture worked but shows the wrong thing
The still is not black, it just shows the wrong window, your desktop wallpaper, or an old view of the app. You shared the wrong surface. This is the most common one and the least dramatic.
When the browser shows the share picker, it offers three tabs: your entire screen, an application window, or a specific browser tab. If you pick Entire Screen and then switch to a different app, the capture follows your whole screen, so you get whatever is in front at the moment of capture. If you pick a specific window and then minimize it, you can get a stale or empty frame.
The fix is to be deliberate about which surface you share:
- To capture one browser tab, choose the Chrome Tab or Edge Tab option and select the exact tab by name. This is the cleanest choice for reviewing a web app or staging site.
- To capture a native app, choose Window and pick that app's window, then bring it to the front before you capture.
- Only choose Entire Screen when you genuinely need everything, and keep the target in view when you click capture.
After you capture, you drag a rectangle to crop the still down to the part that matters, so a slightly wide grab is easy to trim. Cropping is the one image edit available, which keeps the frame honest and readable. If your reviewer needs to point at an exact spot inside the crop, add a numbered pin rather than trying to capture tighter.
When nothing above matches
If the picker appears, permission is granted, the content is not protected, and you picked the right surface but the frame is still wrong, check the browser first. Dictation and capture behave best in Chrome and Edge. Firefox handles capture but not the built-in speech recognition, so reviewers there type their comments. The full checklist for a capture that refuses to cooperate lives on the screen capture isn't working page, including the quick tests to isolate which layer is failing.
One more thing that looks like a failure but is not: a capture that comes back readable but soft or pixelated. That is a resolution issue, not a capture issue, and the captured screenshot is blurry answer walks through raising it.
Once you have a clean frame, the rest is quick. Add a comment by typing or dictating, drop a pin if you need to, and publish. The review gets a public link anyone can open, plus a PDF, Word doc, or markdown version, with no install and no account required to start. If you want to run through the whole flow from scratch, start a new review and capture your first frame.