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How to Fix the MP4 File Won’t Play on Mac Issue

"My MP4 file won't play on my Mac, and I can't figure out why!" This is a common frustration expressed by many Mac users. Trying to watch a video file only to find that it won't play can be a real hassle.

In this guide, we'll explain why your Mac might struggle with MP4 files and offer some easy fixes to make sure you can watch them smoothly. Whether it's updating your software, trying a different media player, or converting the file, we've got you covered.

Part 1: Why MP4 won't Play on Mac?

Before you learn how to fix the issue, it's essential to understand the potential reasons behind the MP4 file won't play on Mac issue. Here are a few triggering reasons:

  • Codec Incompatibility: The MP4 file format supports various codecs (compression/decompression algorithms) for video and audio encoding. If your Mac lacks the necessary codec to decode the MP4 file, it won't be able to play the video.
  • Corrupted or Incomplete Files: Sometimes, MP4 files can become corrupted during download or transfer, rendering them unplayable. Incomplete or truncated files can also cause playback issues.
  • Software/Hardware Compatibility: Certain MP4 files may be encoded with settings that are incompatible with your Mac's software or hardware capabilities, leading to playback failures.
  • Outdated Software: If you're using an outdated version of macOS or a media player that hasn't been updated in a while, it might lack the necessary support for playing certain MP4 files.

Part 2: How to Fix the MP4 Won't on Mac Play Issue

With an understanding of these potential causes, you can now explore the various fixes to resolve the mp4 won't play on Mac issue.

Fix 1: Use Wondershare Repairit to Repair MP4 (Recommended)

If your MP4 file is corrupted or incomplete, using a reliable video repair tool like Wondershare Repairit can be an effective solution. This powerful software can repair corrupted or damaged MP4 files, ensuring smooth playback on your Mac.

  • Repair damaged videos with all levels of corruption, such as video not playing, video no sound, out-of-sync video or audio, playback errors, header corruption, flickering video, missing video codec, etc.

  • Repair full HD, 4K, and 8K videos and support 18 popular formats, including MOV, MP4, M2TS, INSV, M4V, WMV, MPEG, ASF, etc.

  • Repair damaged or corrupted videos caused by video compression, system crash, video format change, etc.

  • Repair critically damaged or corrupted videos available on SD cards, mobile phones, cameras, USB flash drives, etc.

  • Repairit has a quick and advanced scanning mode. You can use either depending on the level of corruption the video file has undergone.

  • No limit to the number and size of the repairable videos.

  • Support Windows 11/10/8/7/Vista, Windows Server 2003/2008/2012/2016/2019/2022, and macOS 10.10~macOS 13.

By repairing the corrupted or damaged MP4 file, Wondershare Repairit can restore its original integrity, ensuring smooth playback on your Mac without any compatibility issues. This approach is particularly effective when other methods fail to resolve the MP4 not playing on Mac issue.

Here's how to use Wondershare Repairit:

Step 1: Open the Repairit tool on your Mac and switch to the “Video Repair” module. Click "Add" to import the problematic MP4 file.

wondershare repairit video repair

Step 2: Once the corrupted MP4 video files are uploaded, select the "Repair" button, and Wondershare Repairit will scan and fix the corrupt files.

repair corrupt video files

Step 3: After the repair is finished, you can preview the repaired MP4 file and save it to your desired location.

Using Wondershare Repairit is highly recommended as it can effectively fix various issues with MP4 files, ensuring seamless playback on your Mac.

Fix 2: Update macOS When MP4 Not Playing on Mac

If MP4 file won't play on your Mac, updating to the newest macOS might fix the issue. Apple often updates its software to fix bugs and improve how it works with different file types, including MP4s.

With the latest macOS, you get updated codecs and better performance, making it more likely your MP4 files will play smoothly. Plus, these updates can solve other known playback issues.

To update your macOS, follow these steps:

Step 1: Tap the Apple icon at the top-left of your screen, then select 'System Preferences'.

Step 2: Head to General > Software Update.

update mac

Step 3: If an update is available, click "Update Now" and follow the on-screen instructions to download and install the latest version of macOS.

Fix 3: Restart Mac When MP4 on Mac Not Playing

Restarting your Mac can often fix the problem if MP4 files won't play. It clears the memory and refreshes the system, possibly getting rid of any glitches or conflicts that were causing the issue. A restart also frees up system resources taken up by other apps, making sure there's enough memory and power for videos to play smoothly.

To restart your Mac, follow these steps:

Step 1: Click on the Apple menu in the top-left corner of your screen and select "Restart."

Step 2: When prompted, click "Restart" to confirm your choice.

restart mac

Step 3: Wait for your Mac to restart completely, then try playing the MP4 file again.

Fix 4: Clear Cache Files When Mac Can’t Open MP4 File

Cache files help apps run faster by storing temporary data, but if they get old or corrupted, they can mess up playing videos like MP4s. Clearing these cache files can fix playback problems by giving your media apps a clean start to work correctly.

To clear cache files on your Mac, follow these steps:

Step 1: Quit any open applications, especially media players or web browsers.

Step 2: Press the "Command + Shift + G" shortcut to bring up the "Go to Folder" window. Type "~/Library/Caches" and click "Go."

clear cache files

Step 3: Locate and delete the cache files for the media player or web browser you're using to play MP4 files.

Step 4: Restart your Mac and try playing the MP4 file again.

Clearing cache files can help resolve issues related to outdated or corrupted data that may be interfering with MP4 playback on your Mac.

Fix 5: Download MP4 Supported Codecs on Mac

If your Mac can't play some MP4 files because it's missing the right codecs, you can fix this by downloading third-party codec packs. These packs add support for more video and audio formats, letting your Mac play a broader variety of media files smoothly.

Here’s what you need to do:

Step 1: Open your video file in QuickTime Player and click on "Show Movie Inspector" in the Windows tab.

show movie inspector video format

Step 2: A window will pop up showing details about your video, like its source, format, frame rates, size, data size, and data rate. Look out for the "Format" section to see the codecs used in your media.

check video format

  • Here are the video codecs QuickTime supports: MPEG-4 (Part 2), H.264, MPEG-2 (OS X Lion or later), H.263, H.261.
  • And here are the audio codecs: HE-AAC, AAC (MPEG-4 Audio), Apple Lossless, and MP3.

Step 3: Check if any of these formats are used in your video. If not, you may need to enable support for the required codec. Alternatively, you can try using third-party applications to help QuickTime recognize different audio and video types.

With the additional codec support and codec packs, your Mac should now be able to play a wider range of MP4 files, resolving cannot play MP4 on Mac issue.

Fix 6: Use an Alternative Video Player When Cannot Open MP4 on Mac

vlc media player for mac

If MP4 files won't play with your Mac's default media players, switching to a third-party video player might help. These dedicated players can overcome compatibility problems that the built-in players might have, thanks to their ability to work with various MP4 encodings and regular updates for new formats and codecs.

Some popular alternative video players for Mac include:

  • VLC Media Player: This free and open-source media player is known for its ability to play a wide variety of video and audio formats, including MP4 files.
  • QuickTime Player: While QuickTime is pre-installed on Macs, you can try updating to the latest version or reinstalling it to ensure you have the most recent codec support.
  • MPlayerX: This free and open-source media player is designed specifically for macOS and supports a wide range of video and audio formats, including MP4.

Part 3: Tips to Play MP4 Files on Mac Seamlessly

While the fixes mentioned above should help resolve most issues related to playing MP4 files on your Mac, there are a few additional tips you can follow to ensure a seamless viewing experience:

  1. Keep your software updated: Regularly update your macOS, media players, and any relevant codecs to ensure you have the latest compatibility and performance improvements.
  2. Check file integrity: Before attempting to play an MP4 file, verify its integrity by checking if the file is complete and not corrupted. You can use file verification tools or try downloading the file again from a trusted source.
  3. Optimize system resources: Close any unnecessary applications and free up system resources before attempting to play large or high-resolution MP4 files. This can help prevent system performance issues that may impact playback.
  4. Convert MP4 files: If all else fails, you can consider converting the MP4 file to a more compatible format for your Mac, such as MOV or AVI, using a video conversion tool. This can help bypass any codec or compatibility issues specific to the MP4 format.

By following these tips, you can ensure a smoother and more reliable MP4 playback experience on your Mac, minimizing the chances of encountering the Mac can't open mp4 issue.

  • Can I repair multiple MP4 files at once using Wondershare Repairit?

  • Yes, Wondershare Repairit supports batch repair, allowing you to repair multiple MP4 files simultaneously, saving you time and effort.

  • Is it safe to clear cache files on my Mac?

  • Yes, clearing cache files is generally safe as long as you follow the proper steps and only delete cache files associated with the relevant applications. However, it's always a good idea to back up important data before making any system changes.

  • Can I play MP4 files in a web browser on my Mac?

  • Yes, most modern web browsers, such as Safari, Chrome, and Firefox, support MP4 playback natively or through browser plugins. However, if you encounter issues, you may need to update your browser or install additional codecs.