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Fix the "moov atom not found" Error

The error means your player cannot find the index at the end of the file. The footage is usually still there. Here is why it happens and how to rebuild the index.

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By Pritibhukhan Borah, Computer Science Engineer · Last updated: 2026-11-02

What does "moov atom not found" mean?

MP4 and MOV files are made of blocks called atoms (also called boxes). The moov atom is the table of contents: it lists every frame of video and audio, their sizes, positions and timing, and the codec settings. FFmpeg, VLC and many editors print moov atom not found when they open a file and cannot find that atom.

The mdat atom, which holds the actual picture and sound, is a separate block. A file can have a perfect mdat and still be unplayable because moov is missing.

Diagram of three MP4 files as bars. A complete file has an ftyp header, an mdat box with video and audio frames and a moov index. An interrupted recording has the same ftyp and mdat boxes but the moov box is missing. After repair the mdat data is unchanged and a new moov index has been rebuilt.
Where the moov atom sits, what an interrupted recording leaves behind, and what a repair rebuilds.

Why the moov atom goes missing

  • Recording ended abnormally. Cameras and phones usually write moov after the footage, when you press stop. A dead battery, crash, full card or removed card means it was never written.
  • The file is incomplete. A download, upload or copy stopped early, so the end of the file (where moov lives) is missing.
  • Failed processing. A conversion, trim or export crashed before finishing.
  • File-system damage. After an unsafe eject the operating system may have lost the final part of the file.

How to fix it

  1. Find a healthy reference videoA working file from the same device with the same settings. It supplies the codec configuration that was inside the missing moov.
  2. Select both files in the repair toolThe corrupted file in box 1, the reference in box 2 of the tool on the home page.
  3. Repair and saveThe tool scans the damaged file's mdat data for frames, builds a new moov and writes a playable MP4.

Why re-encoding or "faststart" does not help

Commands like ffmpeg -i broken.mp4 -c copy fixed.mp4 or -movflags faststart need to read an existing moov; when there is none they fail with the same error. Tools such as untrunc solve it by recovering the frame list from a reference file. This page does the same thing in the browser, without installing anything.

If the fix does not work

  • Pick another reference. The reference must match the corrupted file's codec, resolution and frame rate. A clip recorded in a different mode will not match.
  • Check the file size. A tiny file (for example a few kilobytes) contains no footage to recover.
  • Check the format. Only MP4/MOV/M4V with H.264 or H.265 are supported.
  • Try the original storage. If the file was copied from a card, copy it again, or recover it from the card with data-recovery software before repair.

Related

Have a video that will not play? Repair MP4, MOV and AVI files in your browser, with no upload. Open the repair tool

Frequently asked questions

Is "moov atom not found" the same as "Invalid data found when processing input"?

They often appear together. FFmpeg prints "moov atom not found" first, then "Invalid data found when processing input" because it could not read the file without that index.

Can the moov atom be recovered without a reference file?

Not reliably. Without a reference, the codec settings that were stored in the missing box would have to be guessed. A short healthy clip from the same device removes the guesswork.

Does "moov atom not found" mean my video is gone?

Usually not. The error describes a missing index, not missing footage. If the file is large, most of the recording is probably still inside it.