Please note that we've updated the Mount & Blade II: Bannerlord save file system which requires you to take certain steps in order for your save files to be compatible with e1.7.1 and any later updates. You can find the instructions here.
Were you able to see the crash uploader tool? If you can upload your crash to us we can check it out. Please don't forget to copy the Crash ID and write it here so that we can find it.
More info about the crash uploader tool can be found here.
Have you checked out these threads about our Crash Checklist and Common Issues and Workarounds? They can help you find a solution as well.