MX Player Custom Codec Not Working? Fix It

A follow-up to How to Fix EAC3 Audio Not Supported in MX Player, for everyone who got a custom codec working and then lost it to an app update.

If you have never installed a custom codec, start with that guide instead - it covers the error from scratch.

This page is for the other case: it worked, and now it does not.

Nothing is broken on your phone and your files are fine.

A custom codec is tied to the MX Player build it was made for, so an app update quietly invalidates it.

Why an update breaks a codec that was fine

The custom codec is a decoder library compiled against a specific MX Player version. The app checks that pairing on startup and refuses anything it does not recognise.

The packs are maintained separately from the app, so they always trail it. When MX Player ships a major update there is a window, sometimes weeks, where no matching pack exists yet.

Android usually updates apps in the background, which is why this tends to arrive as a surprise rather than as something you did.

Fix 1: load a codec pack that matches

Check your app version first, from the three-dot menu, then Help and About.

Now open the codec download page and work down from the newest pack, loading each from Settings, Decoder, Custom codec until one is accepted. Two or three attempts is normal and costs a few minutes.

If you need the full walkthrough with the version table, our guide on fixing EAC3 audio not supported in MX Player lays out which pack goes with which app build.

Fix 2: roll MX Player back

If no current pack is accepted, the pack you need has not been published yet. Waiting is one option, going back to a version that works is the other.

Some of these older builds are on our MX Player download page:

Step back one version at a time rather than jumping straight to the oldest. The nearest build that accepts a codec is the one you want, because it keeps the most recent fixes.

How to install an older version safely

1. Uninstall your current MX Player. Android blocks installing an older build over a newer one.
2. Download the APK you picked, then open it and allow installs from your browser when prompted.
3. Open MX Player once to confirm it runs, then load your codec zip from Settings, Decoder, Custom codec.
4. Turn off automatic updates for MX Player in the Play Store, or the update will undo all of this.

That last step is the one people skip, and it is why the problem comes back a fortnight later.

What rolling back costs you

An older build misses later bug fixes and security patches, and some streaming features in the app may stop working.

For a player you use on local files that is a fair trade. If MX Player is also how you watch streaming content, it is less comfortable, and you should treat the rollback as temporary until a matching pack appears.

When to stop and switch

The tell is straightforward: if two codec packs have been rejected and you do not want to roll the app back, there is nothing further to try today.

Players that decode AC3, EAC3 and DTS natively never have this problem, because there is no separate pack to fall out of step. Our roundup of the best media players for EAC3 playback covers the Android options that need no setup.

Quick questions

Match the pack to the app, or step the app back to meet the pack - start with the newest codec pack and tell us in the comments which app and codec pairing worked, so the next reader can skip straight to it.