How to Fix QuickTime Won't Play MP4 Video

Easily fix MP4 that won’t play on Mac QuickTime player or Windows Media Player with Remo Repair tool. You just need to select the unplayable video, click Repair and Preview the fixed video for FREE.

Help! QuickTime won’t play MP4 files?

“Hi, I have a couple of of MP4 files that will not open and play with my QuickTime player. Is it possible to fix this issue because I want to play these MP4 files with QuickTime? Please help!”

Though QuickTime claims to support MP4 format, sometimes you still can’t open MP4 files with QuickTime or the opened .mp4 file only plays sound without picture or QuickTime won’t play MP4 at all. The reason why QuickTime won’t play MP4 video as well as the solution to play any MP4 file with QuickTime on Mac or Windows is explained below.

Reason behind QuickTime won’t play MP4 file

QuickTime won’t play MP4 file properly on Mac OS X can be mainly due to two main parts such as:

  • Codec error: QuickTime unable to open and play .mp4 video saying “MP4 file could not be opened. A required codec isn’t available.” QuickTime only supports MPEG-4 (MP4/M4V).
  • Incompatible devices: Some Macintosh users reported that QT no longer played MP4 file after having updated to latest macOS Sierra. The unsupported drivers or outdated player could be the cause MP4 video not playing on QT.

Effective solution to fix MP4 won't play on Mac QuickTime player


When a media player, be it QT, WMP or VLC can’t play MP4 file even after the installation of necessary codecs and updated drivers on your Mac, then it clearly indicates that the video is corrupt or damaged. To repair damaged MP4 file on Mac, free MP4 file repair tool from Remo Repair is recommended.

Note: Both demo and paid version of Remo Repair tool are similar in operation but the “Save” button is disabled in the demo edition. To save the fixed video files back to your Mac, activate the licensed version.

Characteristics & Benefits of Remo Repair tool

  • Capable of repairing damaged or inaccessible QuickTime MP4 file that is quite large in size
  • It repairs corrupt MP4, MOV and M4V files successfully
  • Easy to use interface with handy options to fix single and multiple damaged MP4 files
  • Fix QuickTime files of video codecs like avc1, mjpeg, mp4v and audio codecs such as RAW, sowt, mp4a
  • Ability to perform MP4 / MOV file fix on SD card, computer’s hard drive, external hard drive, USB and more
  • Provides the preview of repaired video after the repair has been performed successfully
  • Support all versions of Windows and Mac OS X including Windows 10 / macOS Sierra 10.12

To fix QuickTime won't play MP4 file, follow these steps

Free download Remo Repair MOV tool that supports MP4/MOV/M4V video format and install it on your Mac OS X.  After installing, run the software and follow the below guide to learn how to fix QuickTime won't play MP4 video issue.


Step 1: Launch Remo Repair MOV and select the MP4 file that QuickTime won’t play properly by using “Open” option, then click on “Repair” to fix QuickTime won't play MP4 video.

Open QuickTime won't play MP4 file and click Repair

Step 2: Wait patiently until the software automatically fixes the issues in the selected video or click “Abort” option to interrupt the repair process.

View MP4 file repair progress

Step 3: After completion of file repair process, click “Preview Repaired File” option to view the repaired video and click “Save Repaired File” button to save the fixed MP4 file.

Preview & Save MP4 video