Can't open any existing AEP files.

[Acacia27799877xqel]

I started at a new job with a wiped Mac. I installed the lates version of AE (23.1.0 Build 83) and whenever I try and open an exisiting AEP i get several different error messages. I've tried several different files all have the ssame issue.

I have incuded screenshots of the error messages. Literally have mo idea what to do. Others who have new computers are also having the same issue. 

[Mylenium]

Have you actually installed the legacy version of Quicktime? Otherwise I would try to reinstall AE 2023 and also check if the files open in 2022 after installing that as well.

Mylenium

[Warren Heaton]

The project file is fine, it's the source footage that is having issues.

In the Finder, transcode your source video to a format supported in the current version of After Effects.  I recommend transcoding to ProRes.  However, if After Effects is unable to open source file, the Finder may not be able to.  I have had good results with Shutter Encoder (donationware) for transcoding movie files that After Effects will not open as is.  Make sure to use one of the "For Editing" options (I recommend ProRes 422 LT for MP4s).

Don't try to work directly from local cloud storage locations.  Copy to a non-cloud location.  Work, then copy back.  It's not the right type of cloud storage for that.  If you really want to work from cloud storage, subscribe to LucidLink.

[Acacia27799877xqel]

Thank you for helping. I'm a novice with after effects so not sure about trying this confidently. 

It seems like a big process to just try and open an exisiting AEP (of which we have hundreads).