This is a multi-step task and can take from a few seconds to several minutes to complete. Only one set quorum active task can be in progress at any specified time. This error has one of two causes. Either another set quorum task is already in progress, or the internal cluster logic did not accept your request to make the selected disk the active quorum disk.
Check the state of the MDisks and complete any outstanding fix procedures. If another set quorum active task might be in progress, wait for several minutes for that task to complete, and resubmit this task. If you have received this error when there is no other set quorum active task in progress, specify a different disk to replace the current active quorum disk and specify the same quorum index number, and resubmit this task.