After Effects supported video formats
1. If you've already checked that your videos are not damaged, the most likely root cause, of After Effects error can't import file, is that your video codec is not supported by Adobe After Effects. The picture lists the video formats supported by After Effects. As you can see, MOV is included but it says "requires QuickTime", the implementation of MOV support (the capability of coding/decoding MOV) of Adobe Effects is actually based on QuickTime. Also, it requires the installation of QuickTime and good communication between After Effects and QuickTime. Official link for QuickTime Installation: https://support.apple.com/kb/DL837?locale=en_US
2. Already Installed QuickTime?
In that case, your After Effects MOV file damaged unsupported issue could be boiled down to:
1) Communication blocked between After Effects and QuickTime
Fix: Remove/disable third-party firewall programs from the control panel, and try importing MOV into AE again and see if it works.
2) MOV support is interfered by some QuickTime components
Fix: Remove all third party components that you have installed to QuickTime, and add the necessary ones back one by one, until you find the one that causes your AE can't read MOV files.
3) You haven't updated QuickTime for a long time
Fix: Upgrade QuickTime Codec at: https://support.apple.com/kb/dl837?locale=en_US
Or download and install one of the best third-party codec packs at: https://www.codecguide.com/quicktime_installation.htm
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