Michigan Compiled Laws, Chapter 700. Estates and Protected Individuals Code § 700.3302

Sec. 3302. Upon receipt of an application requesting informal probate of a will and after making the findings required by section 3303,  1 the register shall issue a written statement of informal probate. Informal probate is conclusive as to all persons until superseded by an order in a formal testacy proceeding. A defect in an application or procedure relating to the application that leads to informal probate of a will does not render the probate void.