I've just updated pulumi from 0.15.4 to latest... and it wants to replace all my azure resources. I assume this is the role.assignment -> role.Assignment change... is there a way to patch my state file rather than actually replacing everything?

If that is the root cause, then yes, it's definitely possible to patch your state manually. @incalculable-sundown-82514 @microscopic-florist-22719 @bitter-oil-46081 can you verify this is the root issue here, and advise on how to do this upgrade?

i just did a string replace from assignment:assignment to assignment:Assignment and it adopted the existing things just fine

Ah ok, glad this just worked, and sorry for the disruption.