Problem with rendering difficulties since upgrading to PP2022

I have a problem rendering several clips on the timeline of a video that has just been automatically updated to PP 2022. I have colour corrected these on the previous version. The rest of the video has been rendered successfully.The message says 'error compiling movie' and 'unknown error'. Also, there was a previous message about needing to convert the file? I can't find the 2021 version in my autosave either. I don't seem to have been informed about the upgrade, otherwise I would have saved it elsewhere. Not happy. Many thanks for your help.