There are several reasons for this error and below we will consider each of the reasons in detail.

With such a range of accepted file types, it’s surprising and frustrating when QuickTime can’t open a file.

One of the major benefits of Apple’s patented media player, QuickTime, is that it’s free and supports basic video file types. If that happens, your app won't open the file or won't play back its audio or video.' - Official developer Apple Updating the application should easily fix the issue. You might not have the latest version of the QuickTime app installed on your Mac, which is why it cannot play your video. If you cannot play your video file using QuickTime Player, it means your app is either incompatible or outdated. 'Older or specialized media formats might not work in your app, because the format requires software designed to support it. Solution 2: Update QuickTime Player on Mac. But those who expect greater functionality from their media players might find that, occasionally, their QuickTime Player won’t work when trying to open different file types. Most Mac users are happy using the basic programs pre-installed on the operating system, such as Music, QuickTime Player, and iCloud Drive. QuickTime Player Not Working When Trying to Open Files

Quicktime player mac update