We have just done some tests moving projects from Resolve 8.2.2 to Resolve 9.1.1.
In a couple of cases, when importing projects with stills included, Resolve 9 crashes. However if you do not include the stills, it works fine.
We've just sent an email to support, so we'll see what they come up with.
If you spot any other odd things - please let me know!
Best Regards, Chris!