MP4 won’t play on Windows 10 or 11: how to fix it

By the FixMP4 engineering team · Updated October 21, 2026 · Tested on real H.264, HEVC and AAC recordings

On Windows, an MP4 that will not play is most often a missing codec, not a broken file. iPhone, drone and many camera videos use HEVC (H.265), which Windows 10 and 11 do not decode out of the box; the HEVC Video Extensions are a separate download from the Microsoft Store. The second common cause is unsupported audio (AC-3, DTS, PCM). Only if the file fails in every player, including VLC, is it likely to be corrupted, usually by an interrupted recording.

Step 1: try VLC

Install VLC and open the file. VLC includes its own HEVC and audio decoders.

• It plays: the file is healthy. Either keep using VLC or add the missing codec to Windows (Step 2).
• It does not play or shows 0:00: go to Step 4.

Step 2: add HEVC support to Windows

Open the Microsoft Store and search for HEVC Video Extensions (from Microsoft). On many PCs the manufacturer version is preinstalled; otherwise Microsoft sells it for a small fee. Also install AV1 Video Extension (free) if your files are AV1. After installing, restart the Media Player app.

Error code 0xc00d36c4 and messages like "This item was encoded in a format that's not supported (0xc00d5212)" usually point here.

Step 3: check the codecs in the file

Right-click > Properties > Details shows some information; MediaInfo shows all of it. If the video is HEVC and you would rather not install the extension, convert it:

`` ffmpeg -i input.mp4 -c:v libx264 -crf 18 -c:a aac output.mp4 ``

If only the sound is missing, see MP4 has no sound.

Step 4: when the file itself is damaged

Signs of real damage: the recording ended because of a crash, dead battery or full card; the file is large but shows no duration; VLC, FFmpeg and every other player refuse it. Typically the frames are intact but the index (moov atom) was never written.

FixMP4 rebuilds that index locally in your browser on Windows (Chrome, Edge or Firefox), without uploading the video. Add a short healthy clip from the same device as a reference and check the free preview.

Open the free repair tool

Other things to check

• The file is fully downloaded (OneDrive "online-only" files show a cloud icon).
• The path is not on a disconnected network drive or phone connection; copy it to the local disk first.
• The GPU driver is current: hardware decoding issues can show a black screen with sound.

Common Windows messages and what they mean

Windows Media Player, Media Player (new) and Films & TV

Windows 11 ships the new Media Player app, while Windows Media Player Legacy and Films & TV may still be present. They share the same system codecs, so if one fails with an HEVC file the others will too. Installing the HEVC extension fixes all of them at once. VLC, MPV and PotPlayer use their own decoders and are a quick way to separate a codec problem from file damage.

Files from phones, drones and dashcams

• iPhone (HEVC): install the HEVC extension, or set the iPhone to Settings > Camera > Formats > Most Compatible to record H.264 in future. When transferring via the Photos app, iOS can also convert to H.264 automatically (Settings > Photos > Transfer to Mac or PC > Automatic).
• DJI and GoPro: 4K and high bit-rate modes often use HEVC; see fix DJI video and fix GoPro video.
• Dashcams: a clip from the moment the car switched off is often missing its index; see fix dashcam video.

Make the file play everywhere

If you share videos with people on many devices, H.264 + AAC in MP4 is the safest choice:

`` ffmpeg -i input.mp4 -c:v libx264 -crf 20 -preset medium -c:a aac -b:a 160k -movflags +faststart output.mp4 ``

Summary

1. Test in VLC.
2. If VLC plays it, add the HEVC or AV1 extension, or convert.
3. If no player opens it and the recording was interrupted, rebuild the index with a reference clip.

Before you repair anything

Always work on a copy. If the video is on an SD card or phone, copy it to the PC's internal drive first: playback from a slow card reader, a phone connected over MTP, or a network share can stutter or fail in ways that look like corruption. If the copy itself fails partway, the card or cable may be the real problem, and copying again (or using a different reader) is the fix.

Check the file size too. A video that should be several hundred megabytes but is only a few kilobytes, or shows 0 bytes, did not transfer or was never written; see MP4 is 0 bytes. A large file that no player opens and that shows no duration is the classic interrupted recording, which is exactly the case an index rebuild is designed for.

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