Fix: UNDF Error in VLC Media Player (Unsupported Format)

The “UNDF” error in VLC Media Player appears when the application is unable to recognize or decode the file format.

This typically happens due to one of the following reasons:

• Missing or unsupported codecs: VLC may lack the required codec to interpret the file format, especially if the media is encoded using outdated or rare standards.
• Corrupted file structure or encoding issues: If the file is damaged or improperly encoded, VLC may fail to parse it and display this error.
• Compatibility problems with newer VLC versions: Some recent VLC builds have dropped support for legacy codecs, which may prevent certain files from playing properly.
• Misconfigured VLC preferences: Custom or altered VLC settings can sometimes interfere with codec detection or playback.

Now that you know the most likely causes of the UNDF error, let’s move on to the tested solutions.

1. Download an Older Version of VLC Media Player

Many users have resolved the UNDF error by installing an older version of VLC. This is because newer versions often drop support for outdated or less common codecs in favor of modern formats. In contrast, older versions retain support for legacy codecs, making them more compatible with certain older or uncommon media files.

1. Press Windows + R, type appwiz.cpl, and click OK.
2. Find VLC Media Player in the list, right-click it, and select Uninstall.
3. Visit VLC’s official release page.
4. Look for stable versions like VLC 2.2.5 or VLC 3.0.11.
5. Click the Download button for the selected version.
6. Run the installer and complete the installation process.
7. Try playing the file again in VLC to see if the error is resolved.

2. Reset VLC Preferences

Resetting VLC preferences removes all custom configurations and restores the default settings. This ensures VLC falls back to its original codec-handling behavior. This step can often fix playback errors like UNDF that result from misconfigured or conflicting settings.

1. Launch VLC Media Player.
2. Click on Tools in the top menu.
3. Select Preferences from the dropdown.
4. At the bottom of the Preferences window, click Reset Preferences.
5. Restart VLC Media Player.

3. Install the Combined Community Codec Pack

If VLC fails to decode certain formats due to missing or unsupported codecs, installing the Combined Community Codec Pack (CCCP) can help. While VLC includes most essential codecs internally, it may still struggle with niche or older formats better handled through external codec packs.

CCCP extends system-level codec support, allowing VLC and other media players to access a wider range of decoding tools via the operating system. This can resolve playback errors like UNDF when built-in decoding is insufficient.

1. Open your browser and go to this CCCP download page.
2. Click the Download button.
3. Run the downloaded installer and follow the default setup process.
4. Restart your computer after installation.
5. Launch VLC and try playing the same file again.

If none of the above methods work, the file itself may be corrupted or improperly encoded. Try opening it in another media player like PotPlayer or MPC-HC. If it still fails, the issue likely lies with the file, not VLC.