Thank you for important troubleshooting information.
Premiere Elements 14/14.1 on Mac El Capitan
1. There is no guarantee that a project file from an earlier version will open in a later version of the program.
And, there is no backward compatibility in this regard. That is, if you create a project file in an earlier version, edit it in a later version, and then try to open and edit the later version edit in the earlier project, it errors out. Consequently, best to work with a copy of the project file created in the earlier version and try to use the copy in the later version. Better yet to finish projects in the program in which they were created. The lack of backward compatibility appears to explain your 12/12.1 corrupt messages.
2. The following is Adobe's description of its 14.1 Update.
If you feel that there is a one on one relationship between the crashes and applying the 14.1 update, consider uninstalling reinstalling 14 and not doing update to 14.1 until you have a proven 14 or you have no other alternative to update to 14.1 because of problems with 14.
3. Whether or not you used these particular source media before, what are the properties of these files that are being label corrupt or are believed to be involved with the 14/14.1 crashes. What are you doing in the project when the program crashes? What are the pixel dimension of your photos, and how many of them are there in this 40 minutes Timeline content?
Please consider, and then we can decide what next based on the details in your reply.
Add On...Was 12/12.1 used before and now using Mac El Capitan?
re your point 1 ---
I understand backward compatibility isn't promised. And I understand once one goes forward with a new version of an app, likely one ought not expect an old version of the app to handle whatever the new version creates or modifies. However, absent explicit vendor warnings to not do it, it is likely a user will expect the new app version to be able to go forward with whatever had been started in the previous app version, and know he can't "go back" afterward. However, point taken. I will prudently finish the problem project in 12.0, as I have recovered an archived backup (although several days' work older) of that prel file with which to proceed forward. I have several other incomplete projects already started under 12.0, so it may be some time before I can actually migrate to 14. Sometimes getting work out the door takes precedence on getting to play with the new stuff!
re your point 2. ---
I reloaded 14.0 am testing it on another previous (created in 12.0) project without upgrading to 14.1. Several hours of kinda doing all the stuff I had been doing before the 14.1 event, and no problems with 14.0 so far.
re your point 3. ---
Most photos (mostly JPG, a few were PSD out of Photoshop) were cleaned up and set to 16:9 aspect ratio in Lightroom. Most around 4320x2432, some as large as 4608x2592. Perhaps 300 photos and several dozen video clips.
14.1 never gets to the point of loading media; it appears to crash just as it's progress bar reaches the end (100%) loading the suspect prel project file. 12.0 aborts at the same point, although 12.0 gracefully gives an error popup instead of crashing. I infer the crash is due to an error in the prel file, not media files; most of the same media has been used successfully when I test 14.0 on a scratch project left over from 12.0
lastly, I never updated to 12.1, stayed using 12.0 before (Yosemite) and after upgrading to El Capitan.
Thanks sincerely, ATR, for your suggestions.
Thanks for your follow up with important comments and troubleshooting information.
1. Those 300 photos (4320 x 2432 and 4608 x 2592) and several dozen videos in the project need to be looked at as contributing to or causing the instability in your project. What is the resolution of the video?
Consider taking the photo pixel dimension to 1920 x 1080. In that regard, please consider the comments on this in the following...
What is going to be your export choice - export to file saved to the computer hard drive or burn to disc or ISO Image?
2. There have been several Premiere Elements 14/14.1 Mac issues lately that have a wide variety of symptoms including MPEG exports and DVD burns failures.
There is a known Premiere Element 14/14.1 Mac issue called Royalty Activation error that has been pointed to. Please look into Adobe's suggested fix for this particular problem and determine if this applies to your situation. Details included in the following
Please consider, and then we can move forward based on the details in your reply.