Iowa Code § 123A.4: Cancellation.

A brewer or a wholesaler shall not cancel, fail to renew, or otherwise terminate an agreement unless the party intending that action has good cause for the cancellation, failure to renew, or termination, has made good faith efforts to resolve disagreements, and, in any case in which prior notification is required under section 123A.3, the party intending to act has furnished the prior notification and the other party has not eliminated the reasons specified in the notification for cancellation, failure to renew, or termination, within the periods provided in section 123A.3, subsection 4, paragraph “d”.