During desired nodes updates the system validates that the provided node settings are valid in order to avoid boot looping issues. If one of the node settings depends on a secure setting, the validation fails even when the secure setting is present and correct.
server/src/main/java/org/elasticsearch/node/Node.java
coordinator.start(); 
        clusterService.start();
        assert clusterService.localNode().equals(localNodeFactory.getNode())
            : "clusterService has a different local node than the factory provided";
        transportService.acceptIncomingRequests();
        /*
         * CoordinationDiagnosticsService expects to be able to send transport requests and use the cluster state, so it is important to
         * start it here after the clusterService and transportService have been started.
         */
        injector.getInstance(CoordinationDiagnosticsService.class).start();
        coordinator.startInitialJoin();
        final TimeValue initialStateTimeout = INITIAL_STATE_TIMEOUT_SETTING.get(settings());
        configureNodeAndClusterIdStateListener(clusterService);
        if (initialStateTimeout.millis() > 0) {
            final ThreadPool thread = injector.getInstance(ThreadPool.class);
            ClusterState clusterState = clusterService.state();
            ClusterStateObserver observer = new ClusterStateObserver(clusterState, clusterService, null, logger, thread.getThreadContext());
            if (clusterState.nodes().getMasterNodeId() == null) {
                logger.debug("waiting to join the cluster. timeout [{}]", initialStateTimeout);
                final CountDownLatch latch = new CountDownLatch(1);
                observer.waitForNextChange(new ClusterStateObserver.Listener() {
                    @Override
                    public void onNewClusterState(ClusterState state) {
                        latch.countDown();
                    }
                    @Override
                    public void onClusterServiceClose() {
                        latch.countDown();
                    }
                    @Override