Firefox stuck on 'Hello' YouTube screen? Fix it now

Quick answer: Clear Firefox cache (Ctrl+Shift+Delete), check if uBlock Origin is the culprit (disable it temporarily), and if that fails, delete the storage/default folder in your Firefox profile.

The 'Hello' screen—where YouTube shows a giant grey 'Hello' and the video never loads—isn't a real error. It's a loading placeholder that gets stuck when Firefox can't fetch the video's metadata properly. This happens most often after a Firefox update, or when you've got an ad blocker that's too aggressive, or when the browser's cache has gone stale. I've seen it trigger right after you click a YouTube link from Reddit or Twitter, specifically in Firefox 121+ on Windows or Linux. The video sits there, the spinning circle stops, and you're left staring at 'Hello'. Let's fix it.

Step-by-step fixes

Step 1: Clear cache and cookies for YouTube

1. Open Firefox and go to YouTube (don't close the tab yet).
2. Click the padlock icon in the address bar (left side of the URL).
3. Click Clear cookies and site data.
4. A popup will appear—click Remove. After this, the page will reload. You should see the YouTube homepage load fresh. Then click a video. If it still shows 'Hello', move to Step 2.

Step 2: Disable uBlock Origin (or other ad blockers) temporarily

1. Click the uBlock Origin icon in the toolbar (looks like a red shield).
2. Click the big power button that says Permanently disable uBlock Origin for this site.
3. Refresh the YouTube tab (Ctrl+R or F5).
4. Try playing the video again. If it loads now, uBlock Origin was the problem. You can re-enable it after, but you might need to whitelist YouTube. To do that, right-click the uBlock icon, select Dashboard, go to My filters, and add @@||youtube.com^$document (this allows YouTube to work without uBlock blocking its scripts).

Step 3: Full cache nuke (the surefire fix)

1. In Firefox, type about:profiles in the address bar and press Enter.
2. Find the profile marked This is the profile in use. Look at the Root Directory row—click Open Directory (on Windows) or Show in Finder (on Mac). A file explorer window will open.
3. Close Firefox completely. File > Exit. Do not skip this—if Firefox is open, the folder can't be modified properly.
4. In that profile folder, look for a folder called storage. Double-click it.
5. Inside storage, find the folder named default. Delete the entire default folder. Don't worry—this only removes local website storage (like YouTube's cache), not your bookmarks or passwords.
6. Reopen Firefox and go to YouTube. The 'Hello' screen should be gone. Videos will load normally.

Alternative fixes if the main ones fail

Check for Firefox updates

YouTube's code changes constantly. An outdated Firefox can break video loading. Go to Menu (three horizontal lines in the top-right) > Help > About Firefox. Firefox will check for updates and install them automatically. Restart the browser after.

Try a private window

Open a new private window (Ctrl+Shift+P) and go to YouTube there. If the video loads fine, the issue is with your main profile's cache or extensions. You can then reset your main profile (Step 3 above) or disable all extensions one by one to find the troublemaker.

Reset the Firefox profile

If nothing works, you can refresh Firefox. This keeps your bookmarks and passwords but resets extensions, settings, and caches. Go to Menu > Help > More Troubleshooting Information > click Refresh Firefox.... Follow the prompts. After this, you'll need to reinstall extensions, but it's a clean slate.

Prevention tips

You can stop this from happening again. First, keep Firefox updated—turn on automatic updates in Settings > General > Firefox Updates. Second, if you use uBlock Origin, don't enable 'Hard mode' or 'Medium mode' unless you know what you're doing—those break YouTube frequently. Third, clear your cache every couple of weeks. It's quick: Ctrl+Shift+Delete, check Cache and Cookies, set time range to 'Everything', click Clear Now. Do that after a Firefox major version update (like from 123 to 124) and you'll likely never see that 'Hello' screen again.

One last thing: if you're on an older OS like Windows 7 or macOS 10.13, Firefox might not be getting updates at all. That's a bigger problem. Upgrade your OS or switch to a newer browser like Chromium-based Edge or Brave for YouTube. Firefox can only do so much with old bones.