What happens if you have an car crash and thought you were insured but it was cancelled?

Assuming that you are at fault for the collision but were uninsured, you would be personally responsible for the damages proximately resulting from the collision. "Fault" equates with the legal theory of "negligence". Negligence is the failure to adhere to that degree of care that a hypothetical reasonable person would use under similar circumstances. "Fault" could also be an intentional act that results in the collision; in that event, you would also be personally responsible. That said, insurance covers only negligent acts. Therefore, if the damage resulted from an intentional act, the existence or nonexistence of insurance is immaterial.

No coverage is no coverage, no matter what you thought.