A header for an agricultural harvester having a cutterbar lockout control mechanism that can be set in flex or rigid modes independent of the position of the cutterbar assembly. The cutterbar lockout control mechanism may be set to flex or rigid modes without the operator having to reach under the header, and the operator may reposition the cutterbar assembly without leaving the cab. Also, a method for setting the operating mode of a cutterbar assembly of a header for an agricultural harvester, and a method for repositioning a cutterbar assembly of a header for an agricultural harvester.