How To Fix YouTube Not Working On Firefox In 2026

YouTube videos that stay black, spin forever or refuse to play in Firefox are almost always caused by something local, such as an add-on, a cached file or a graphics setting.

Because YouTube officially supports Firefox, the problem is usually fixable without leaving the browser.

Work through the steps below in order and you can usually fix YouTube not working on Firefox in about 10 minutes.

Which fix matches your symptom?

What you see	Most likely cause	Try this fix
Video plays in another browser but not Firefox	Add-on or Firefox setting	Fixes 4 and 5
Black screen or green flicker	Hardware acceleration or graphics driver	Fix 6
Page loads but video never starts	Blocked autoplay	Fix 7
Movies or rentals will not play	DRM setting off	DRM section below
Endless buffering	Slow connection	Fix 2
Nothing helps	Damaged profile settings	Fix 9 (Refresh)

Why does YouTube stop working in Firefox?

The usual causes are limited, and each has a matching fix below.

Extensions that block or rewrite page content.
Stale cache or cookies for the YouTube site.
Hardware acceleration conflicting with a graphics driver.
Autoplay or DRM settings that block playback.
An outdated Firefox, since YouTube asks for the latest release.

Fix 1: Reload the page and restart Firefox

A one-off playback glitch often clears with a reload.

Press F5 to reload the tab.
Close Firefox completely and reopen it.
Open the video again.

Fix 2: Check your internet speed

YouTube lists the minimum connection speeds for smooth playback.

What you watch	Minimum speed	Browsers YouTube lists
Standard videos	500 Kbps	Latest Chrome, Firefox or Safari
Movies, TV shows and live streams	1 Mbps	Latest Chrome, Firefox or Safari

If other devices on your network also buffer, restart the router before changing anything in Firefox.

Fix 3: Update Firefox

YouTube asks for the latest browser release, so an old Firefox can fail.

Click the menu button, then Help, then About Firefox.
Wait while Firefox checks for and downloads updates.
Click Restart when prompted.

If you installed Firefox from a Linux package manager or the Microsoft Store, updates arrive through that system instead.

Fix 4: Test in Troubleshoot Mode

Troubleshoot Mode starts Firefox with add-ons and hardware acceleration switched off, so it shows which one is to blame.

Click the menu button, then Help, then Help and Report.
Choose Troubleshoot Mode… and click Restart.
Open the YouTube video.

Plays fine: an add-on or hardware acceleration is the cause, so continue with Fix 5 and Fix 6.
Still broken: skip ahead to Fix 7.

To leave, exit Firefox and start it normally; your add-ons and settings come back.

Fix 5: Disable your extensions one by one

Ad blockers, script blockers and video downloaders are the usual suspects.

Click the menu button, then Add-ons and themes, then Extensions.
Click an extension’s toggle to turn it off.
Reload YouTube and test.
Repeat until the video plays, then remove the culprit with the three-dot menu and Remove.

Fix 6: Turn hardware acceleration off

Graphics-driver conflicts can cause black frames or stuttering.

Open the menu and choose Settings.
In General, find the Performance section under Tabs and browsing.
Uncheck Use recommended performance settings.
Uncheck Hardware acceleration.
Restart Firefox.

Mozilla notes that Firefox hides this option when your graphics driver is not compatible.

Fix 7: Allow autoplay for YouTube

Blocked autoplay can leave a video waiting for a click.

Open Settings, then Privacy & Security, then Permissions.
Click Settings… next to Autoplay.
Set the default or the youtube.com entry to Allow Audio and Video.
Click Save Changes.

You can also click the autoplay icon in the address bar while a YouTube tab is open.

Fix 8: Clear cookies and site data

Damaged site data can break the player for one site only, so start with YouTube alone.

Go to Settings, then Privacy & Security, then Cookies and Site Data.
Open the site data manager and search for youtube.
Click Remove All Shown, then Save Changes.

Removing site data signs you out of YouTube, so have your Google login ready.

Do movies and rentals need the DRM setting?

Firefox uses Google’s Widevine module to play protected video on desktop.

Open Settings and find Digital Rights Management (DRM) Content, in General or under Tabs and browsing > Media.
Check Play DRM-controlled content.
If it was already on, uncheck and recheck it to reload the components.

Mozilla also names Avast AntiTrack as a known cause of DRM problems.

Fix 9: Refresh Firefox as a last resort

Refresh gives you a clean profile configuration while keeping your core data.

Open the menu, then Help, then Help and Report.
Choose More troubleshooting information.
Click Refresh Firefox… and confirm.

Kept after a refresh	Removed after a refresh
Bookmarks, history, passwords, cookies	Extensions and themes
Web form autofill, personal dictionary	Website permissions and modified preferences
Your old profile is saved to the desktop as “Old Firefox Data”	Toolbar customizations and added search engines

Delete the Old Firefox Data folder when you are done, because Mozilla warns it holds sensitive information.

Which fixes cost you data?

Most steps are reversible, but a few change what Firefox remembers.

Fix	What you lose	Reversible?
Troubleshoot Mode	Nothing; add-ons return when you exit	Yes
Removing an extension	That extension and its settings	Reinstall it
Clearing YouTube site data	Your YouTube sign-in on that browser	Sign in again
Refresh Firefox	Extensions, site permissions and modified preferences	Partly, via the Old Firefox Data folder

What if YouTube still will not play?

Check that security software is not blocking Firefox, then test YouTube in another browser to confirm the fault is Firefox itself.

If Firefox also crashes, see our guide to Firefox keeps crashing, or for connection errors our PR_CONNECT_RESET_ERROR fix.

If the problem is the app and not the browser, try YouTube not working on Roku.