MX Player “Cannot Play This File” Error: Why It Happens and How to Fix It

You tap a video in MX Player and get the dreaded message: “Cannot play this file.” It can feel random, especially when the same file plays fine on a different phone, in another app, or used to work before an update. In reality, MX Player is usually telling you something specific: the file’s codec is unsupported, the file is damaged, the container is weirdly authored, permissions block access, or the device cannot decode it reliably with the chosen decoder.

This guide breaks down the most common, real-world causes and gives practical fixes you can try in minutes, plus deeper solutions when the problem is a codec or encoding issue.

1. What The Error Actually Means (And What It Does Not)

“Cannot play this file” is a catch-all playback failure message. MX Player can fail before playback starts for multiple reasons: it cannot read the file, it cannot demux the container, it cannot decode the audio or video stream, it cannot render due to hardware limitations, or it hits a protected/DRM source that third-party players cannot handle.

It does not automatically mean “the video format is wrong.” Two files can both be “MP4” yet behave completely differently, because “MP4” is just a container. Inside that container are separate streams, typically:

• Video codec (examples: H.264/AVC, H.265/HEVC, VP9, AV1)
• Audio codec (examples: AAC, MP3, AC-3, E-AC-3, DTS)
• Subtitles (examples: SRT, SSA/ASS, PGS)
• Metadata and timing information

If any critical piece is unsupported or malformed, MX Player may refuse playback.

2. The Most Common Reasons MX Player Cannot Play a File

2.1 Unsupported Audio Codec (A Frequent Culprit)

A very common scenario is: video plays elsewhere (or in MX Player on some devices) but fails on yours because the audio stream is encoded with a codec MX Player cannot decode in your installed version.

Historically, licensing restrictions have affected which codecs are bundled with some Android media players. As a result, formats like AC-3 (Dolby Digital) or DTS may not play without additional codec support, depending on the app build and device.

Symptoms often include either a total playback failure or playback with no sound. Some files will trigger “Cannot play this file” immediately if the player can’t initialize the audio pipeline.

2.2 Unsupported Video Codec Or Profile Level

Even if “H.265” is supported in general, the specific encoding settings can break compatibility. Examples include:

• 10-bit HEVC (Main10) on older devices that only support 8-bit decoding
• Very high resolution or bitrate (for example, 4K high-bitrate files on mid-range phones)
• Unusual H.264 profiles/levels that exceed your device’s hardware decoder capabilities

When hardware decoding fails, MX Player may still succeed by switching to software decoding, but not always if the device is too slow or the file is too demanding.

2.3 The File Is Corrupted Or Incomplete

Corruption is more common than it looks. A download might have been interrupted, a transfer might have failed, or the storage could have issues.

• If the video is a partially downloaded file, it may not contain a complete header or index.
• If it was transferred over USB or messaging apps, it may have been truncated.
• If it’s on a failing SD card or unstable USB-OTG drive, read errors can occur.

In these cases, some players attempt recovery; others simply stop and report that they cannot play it.

2.4 Container Issues (MP4 vs MKV vs “Badly Authored” Files)

Containers (MP4, MKV, AVI, MOV) define how streams are packaged. A file can be “MP4” but have odd timestamping, missing “moov atom” placement (common with improperly created MP4s), or inconsistent stream metadata.

MKV is flexible, but that flexibility also means more variety in how files are authored. Some edge-case MKVs can fail on certain demuxers.

2.5 Android Storage Permissions Or Scoped Storage Limitations

On modern Android versions, apps must follow tighter storage rules. If MX Player does not have permission to access the folder where the video sits, or if the file is in a protected location, it may fail to open the file.

This can show up after:

• An Android OS update
• Reinstalling MX Player (permissions reset)
• Moving files to a new folder on internal storage or SD card

2.6 Problematic Subtitles Or External Subtitle Encoding

Less common, but real: a subtitle file can crash playback initialization or cause odd failures, especially with malformed SSA/ASS styling or unusual character encoding. If the video plays without the subtitles enabled, you have a strong clue.

2.7 Hardware Acceleration Problems (HW Decoder Bugs)

Hardware decoding is efficient, but device-specific decoder bugs exist. Some phones struggle with particular encodes, frame reordering patterns, or bitstreams. Switching the decoder from HW to SW (software) is often the fastest fix.

2.8 DRM-Protected Content

If the file or stream is DRM-protected (common with many subscription services), third-party players generally cannot decrypt it. In those cases, you typically must use the official app or a player that integrates the required DRM framework for that service.

3. Quick Fix Checklist (Try These First)

3.1 Confirm The File Plays Elsewhere

Before changing settings, determine whether the file is actually valid:

• Try playing it in another player on the same device (for example, the system video player).
• Try playing it on a PC.

If it fails everywhere, it is likely corrupted or incomplete. If it plays elsewhere but not in MX Player, it is likely a codec/decoder/container issue or MX settings.

3.2 Update MX Player

App updates can add fixes for demuxing bugs, Android storage changes, and decoder stability. Update MX Player from your official app store, then try again.

3.3 Restart The App And Clear Cache (Not Data Yet)

On Android:

1. Force stop MX Player.
2. Open Android Settings, go to Apps, choose MX Player.
3. Clear cache.

Clearing cache can resolve stuck thumbnails, indexing issues, or temporary decode failures.

3.4 Move The File To Internal Storage And Try Again

If the file is on an SD card, USB drive, or a network-mapped location, copy it to internal storage and test. This eliminates file access and read stability issues.

3.5 Check Permissions

Ensure MX Player has the needed access:

• In Android Settings, grant Photos and Videos or Files and Media permissions (wording varies by Android version).
• If you use SD card storage, confirm MX Player is allowed to access that external storage location.

4. Decoder Fixes Inside MX Player (Most Effective Settings Changes)

4.1 Switch Between HW And SW Decoding

Many playback failures are hardware decoder related. If you can open the file at all, try switching the decoder:

• Try HW (hardware) decoding first for efficiency.
• If it fails, try SW (software) decoding.
• If available, try HW+ (some builds include variations that can help).

If SW decoding works but stutters, the device may be too slow for that file’s resolution/bitrate, and you may need to re-encode the video to a lighter format (covered later).

4.2 Toggle Audio Decoder Options

If the video fails instantly, the audio codec may be the issue. Some builds and devices behave better when you switch audio decoding behavior. If MX Player offers an audio decoder toggle (device-dependent and version-dependent), try changing it and re-test.

4.3 Disable Or Change Subtitle Rendering Temporarily

If the file plays only when subtitles are off, test with:

• No subtitles enabled
• A different subtitle file (for example, an SRT)
• Renaming the subtitle file to match the video filename exactly (common matching behavior)

If you suspect subtitle encoding issues, convert subtitles to UTF-8 and remove unusual styling.

5. Codec Pack And “Missing Codec” Situations (What You Can Do Safely)

5.1 Understand The Role Of Codecs

MX Player can decode some formats internally and can also rely on device decoders. If the audio/video stream requires a codec that is not available, you will see errors. In some cases, MX Player indicates a specific codec is missing, and it may suggest a compatible codec pack depending on the distribution and device CPU architecture.

Because codec availability and licensing vary by region, device, and app distribution channel, the safest approach is:

• Prefer supported, widely compatible codecs (H.264 for video, AAC for audio) when you control the file creation.
• If you do not control the file, consider re-encoding it or remuxing it into a better-supported combination.

5.2 Identify The Actual Codec In Your File

You will get much faster results if you confirm what the file contains. Use a tool such as MediaInfo on a computer to check:

• Video codec and profile (H.264 High, HEVC Main10, etc.)
• Audio codec (AAC, AC-3, DTS, etc.)
• Container (MP4, MKV)

Once you know which stream is problematic, you can fix only that part, rather than re-encoding everything blindly.

6. Repair Or Recreate The File (When Settings Won’t Fix It)

6.1 Re-Download Or Re-Transfer The Video

If the file came from the internet, re-download it fully. If it came from a PC, transfer again using a reliable method (for example, direct USB file transfer) and verify file size matches the source.

6.2 Remux Without Re-Encoding (Fast When The Streams Are Fine)

If the audio and video streams are supported but the container is problematic, remuxing can fix playback while keeping the original quality.

Examples of remuxing goals:

• MKV to MP4 (or MP4 to MKV) to improve compatibility
• Rewriting MP4 metadata so it streams and plays correctly

Tools such as FFmpeg can remux quickly because it copies the streams without re-encoding when compatible.

6.3 Re-Encode To A Known-Compatible Format (Most Reliable)

If the codec itself is the issue, re-encoding is the most dependable fix. A “safe” baseline for broad Android compatibility is typically:

• Container: MP4
• Video: H.264 (AVC)
• Audio: AAC

HandBrake is a user-friendly choice for this. If you need maximum device compatibility, consider using a built-in preset aimed at mobile devices, then adjust resolution or bitrate if needed.

6.4 Convert Only The Audio (When Video Is Fine)

If the video stream is H.264/H.265 and decodes fine but the audio is AC-3/DTS/E-AC-3 and causes failure, you can convert only the audio to AAC and keep the original video stream. This preserves video quality and speeds up the process.

7. A Practical Troubleshooting Flow (So You Don’t Waste Time)

Use this order to converge quickly:

1. Test the file in another player on the same device.
2. If it fails everywhere, re-download or replace the file.
3. If it plays elsewhere but not MX Player, update MX Player and clear cache.
4. Move the file to internal storage and confirm MX permissions.
5. Switch HW to SW decoding.
6. Disable subtitles temporarily.
7. Inspect codecs (MediaInfo) and decide: remux or re-encode.

8. Common File Types And What Usually Works Best

8.1 Compatibility Table For Quick Decisions

The table below is not a guarantee, because device decoders and MX Player builds vary. But these combinations are widely compatible across Android devices and players.

8.2 Why “Same Extension” Does Not Mean “Same Playability”

Two “.mp4” files can contain entirely different audio and video codecs. One might be H.264 + AAC (usually fine), while another might be HEVC Main10 + E-AC-3 (often problematic on some setups). If you treat the extension as the format, you can chase the wrong solution.

9. FAQs About The MX Player “Cannot Play This File” Error

9.1 Why Does The Video Play In VLC But Not In MX Player?

VLC bundles a very wide range of software decoders, so it can play many files even when hardware decoding is unavailable. MX Player can also use software decoding, but its supported codec set and the way it integrates with Android decoders can differ by version and device.

9.2 Why Did This File Work Before, But Not After An Update?

After updates, changes in decoder behavior, Android storage rules, or app permission prompts can affect playback. Re-check permissions, switch HW to SW decoding, and retest the file from internal storage.

9.3 Is The File Definitely Corrupted If I See This Error?

No. Corruption is one possibility, but unsupported codecs, unsupported profiles, container problems, or permissions can trigger the same message. Testing the file in another player and inspecting codecs are the fastest ways to confirm.

9.4 What Is The Fastest “Guaranteed” Fix?

If you are allowed to modify the file, re-encoding to MP4 (H.264 video + AAC audio) is the most universally reliable approach. It trades time and sometimes a little quality for maximum compatibility.

9.5 Can Cloud Or Network Files Trigger This Error?

Yes. If the connection is unstable, if the file is not fully downloaded for offline playback, or if the provider uses a format MX Player cannot handle, you can see playback failures. Download the file fully to internal storage and test again.

10. When To Stop Troubleshooting And Choose A Different Player

If the file is important and you cannot re-encode it, it can be more efficient to use a player with broader built-in decoding support. If the issue is DRM, you often must use the official service app. If the issue is a rare codec or exotic profile, a different player may handle it better than trying dozens of toggles.

That said, in most everyday cases, one of the following resolves the MX Player error quickly:

• Switching HW to SW decoding
• Fixing permissions and moving the file to internal storage
• Re-downloading a complete, uncorrupted copy
• Re-encoding to H.264 + AAC in MP4

Citations

• Android Developers. Storage updates and scoped storage guidance. (Android Developers)
• FFmpeg Documentation. General usage and stream copying concepts. (FFmpeg)
• HandBrake Documentation. Overview of encoding and presets. (HandBrake)
• MediaInfo. Tool for inspecting container and codec details. (MediaArea)
• ISO Base Media File Format (MP4) overview and structure references. (ISO)