This error is weird. It's never happened to me, but I'm on macOS. This issue seems to hit some people on Windows. Why do you suppose it happens? I'd like to get to the bottom of it to file a bug. Let me know about any ideas you have, OK?
Thanks, Kevin
Kevin Monahan - Sr. Community and Engagement Strategist – Adobe Pro Video and Audio
don't give us more information about your video clips maybe you should tell us what kind of videos you are using that framerate or some detail of the mask you are trying to create. Try to create a new project and try again with the same clips
I've moved this from the poorly named Community Help forum (which is the forum for issues using the forums) to the Premiere Pro forum so that proper help can be offered.