The error message is saying that there is corruption at frame No. 8314 that caused the export to fail. It is probably a black frame. Expand your timeline full out and slowly scroll through it in the area of frame No. 8314. Look for black frames, white flashes, artifacts and any other indications of corruption. Cut out any that you find and export again.
You can find where frame No. 8314is located by dividing the frame rate of your project into 8314. That will tell you the time point in seconds at which the frame appears.
If you want to preserve your original project, you can duplicate the project and work with the duplicate.
Another thing that you can try is deleting preferences. Open iMovie while holding down the Option and Command keys and select to delete preferences in the box that appears. iMovie will open in a new blank library. Reopen your old library to get back to your projects. It is a safe procedure. Now see if you can export.
I don't know what is causing the Keynote export failure. There may be corruption in a frame in one of the clips that is causing the export to abort, much the same as the iMovie issue. Also the very high bitrate ProRess 4444 may be causing it. Try exporting with a lower bitrate format. Updating Keynote to current version might cure it as well.
-- Rich
