@@ -15,6 +15,9 @@ const (

 	// errSwarmCertificatesExpired is returned if docker was not started for the whole validity period and they had no chance to renew automatically.

 	errSwarmCertificatesExpired notAvailableError = "Swarm certificates have expired. To replace them, leave the swarm and join again."

+

+	// errSwarmNotManager is returned if the node is not a swarm manager.

+	errSwarmNotManager notAvailableError = "This node is not a swarm manager. Worker nodes can't be used to view or modify cluster state. Please run this command on a manager node or promote the current node to a manager."

 )

 type notFoundError struct {

@@ -26,9 +26,13 @@ func (c *Cluster) Init(req types.InitRequest) (string, error) {

 	defer c.controlMutex.Unlock()

 	if c.nr != nil {

 		if req.ForceNewCluster {

+

 			// Take c.mu temporarily to wait for presently running

 			// API handlers to finish before shutting down the node.

 			c.mu.Lock()

+			if !c.nr.nodeState.IsManager() {

+				return "", errSwarmNotManager

+			}

 			c.mu.Unlock()

 			if err := c.nr.Stop(); err != nil {