The rank must be in the unassigned state before it can be assigned. This error occurs most frequently when configuration of a rank has been initiated, but has not yet completed.
If the rank is in configuring state, wait until the rank status is changed to unassigned, and then resubmit the task. If the rank is in any other state, take the necessary steps to place it in the unassigned state, and then resubmit the task.