AC-3 (Dolby Digital) audio not playing in Windows 11: why and how to fix it

Find your symptom

What you see	Likely cause	Fix
Video plays but has no sound (often MKV, MP4 or DVD rips)	No AC-3 decoder in Windows	Play it in VLC or another player with its own decoders
A .ac3 audio file won’t open	No AC-3 decoder in Windows	Use VLC
A game or app closes on launch or during playback since late September 2026	Known issue from KB5124010	Install KB5127648 or later
No sound from anything at all	Device or driver, not the codec	See USB audio Code 10 fixes and check your sound output

Why AC-3 stopped working

Microsoft’s Codecs in Media Player page describes AC-3 as the multi-channel (surround sound) codec also known as Dolby Digital, and says that beginning with Windows 11 version 24H2 it “is no longer included with Windows”. It adds two exceptions:

• If you upgraded from an earlier version of Windows, the AC-3 codec is kept.
• Many device manufacturers pre-install an AC-3 codec on their PCs.

So the problem mostly affects clean installs of 24H2 or later, PCs built without a maker’s codec, and self-built PCs. Microsoft doesn’t give a reason for the change, and its page doesn’t say whether Dolby Digital Plus (E-AC-3) is affected in the same way.

Check your Windows version

Open Settings > System > About or press Win+R and run winver. Version 24H2, 25H2 or 26H2 means the change can apply to you. There’s no official setting that shows whether an AC-3 codec is installed, so the practical test is to play a file you know has a Dolby Digital track in the Windows Media Player app. If the picture plays and the sound doesn’t, the codec is missing. If you’re planning an upgrade, see how to install Windows 11 26H2.

Easiest fix: use a player with its own decoder

Players that bundle their own decoders don’t depend on the Windows codec. VideoLAN’s VLC feature list includes AC-3 (A/52) and E-AC-3. Download VLC only from videolan.org, not from mirror or bundle sites. Microsoft itself notes that many modern apps include their own audio decoding components, which is why most current players and streaming apps keep working.

If you must use an app that relies on Windows, such as some older editors, you can convert the AC-3 track to a format Windows plays, like AAC, with a converter you trust. Keep the original file until you’ve checked the result.

Get the codec from your PC maker

Because many makers pre-install AC-3 support, check your PC maker’s support page for your model. MSI, for example, says in a support FAQ that notebooks shipped with 24H2 keep AC-3 support, while clean installs don’t. If you clean-installed Windows on a branded PC, the maker’s own recovery image may bring their codec back, but check with the maker first, because a recovery reinstall wipes the PC.

Avoid unofficial codec installers

Some guides suggest third-party tweak tools or Dolby app packages downloaded from file-sharing sites and installed by sideloading. These don’t come from Microsoft or Dolby, can be bundled with other tools, and may trigger Windows security warnings. If Smart App Control blocks one, that’s a reason to stop rather than work around it; see Smart App Control blocked an app. A player with its own decoder is the safer route.

Apps closing after the September 2026 update

This is a separate, now fixed problem. Microsoft’s release health page lists it as “Applications which require AC-3 audio decoding might close unexpectedly”.

• Caused by: the optional preview update KB5124010 (September 22, 2026; builds 26100.9550 and 26200.9550, and 26300.9550 for 26H2 on September 29).
• Affected: Windows 11 24H2, 25H2 and 26H2.
• Symptoms: apps that use Windows’ AC-3 decoding failed to launch, closed without warning, or closed when you used a feature such as playing music. Microsoft says these included games, media players and some productivity apps, mostly older ones.
• Fixed by: the October 13, 2026 security update KB5127648 (builds 26100.9711, 26200.9711 and 26300.9711) and later updates.

Microsoft lists no workaround, so update. Open Settings > Windows Update, select Check for updates, install everything offered and restart. Then confirm with winver that your build ends in .9711 or higher. If updates don’t show up, see how to force Windows Update.

Related guides

• How to get and install Windows 11 version 26H2 (the 2026 Update)
• How to force Windows Update to check and install updates
• Smart App Control blocked an app: what it means and what to do
• USB audio device shows Code 10 in Windows 11: how to fix it
• No sound in Windows 11: how to fix speakers and headphones

Official sources

• Microsoft: Codecs in Media Player
• Microsoft: Windows 11, version 24H2 resolved issues (release health)
• VideoLAN: VLC features