Michigan Compiled Laws, Chapter 450. Corporations § 450.3051

Sec. 1051. (1) A foreign corporation that conducts affairs in this state without a certificate of authority shall not maintain an action or proceeding in any court of this state until the corporation obtains a certificate of authority. An action commenced by a foreign corporation that does not have a certificate of authority shall not be dismissed if the foreign corporation obtains a certificate of authority before the order of dismissal.If an action or proceeding is dismissed because a foreign corporation does not have a certificate of authority, the order of dismissal shall be without prejudice to the recommencement of the action or proceeding by the foreign corporation after it obtains a certificate of authority. This subsection applies to the foreign corporation and to any of the following:

(2) Failure of a foreign corporation to obtain a certificate of authority to conduct affairs in this state does not impair the validity of a contract or act of the corporation, and does not prevent the corporation from defending an action or proceeding in a court of this state.