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
import org.elasticsearch.action.search.SearchPhaseController;
import org.elasticsearch.action.search.SearchTransportService;
import org.elasticsearch.action.support.TransportAction;
import org.elasticsearch.action.update.UpdateHelper;
import org.elasticsearch.bootstrap.BootstrapCheck;
import org.elasticsearch.bootstrap.BootstrapContext;
import org.elasticsearch.client.internal.Client;
import org.elasticsearch.client.internal.node.NodeClient;
import org.elasticsearch.cluster.ClusterInfoService;
import org.elasticsearch.cluster.ClusterModule;
import org.elasticsearch.cluster.ClusterName;
import org.elasticsearch.cluster.ClusterState;
import org.elasticsearch.cluster.ClusterStateObserver;
import org.elasticsearch.cluster.InternalClusterInfoService;
import org.elasticsearch.cluster.NodeConnectionsService;
import org.elasticsearch.cluster.action.index.MappingUpdatedAction;
import org.elasticsearch.cluster.coordination.CoordinationDiagnosticsService;
import org.elasticsearch.cluster.coordination.Coordinator;
import org.elasticsearch.cluster.coordination.MasterHistoryService;
import org.elasticsearch.cluster.coordination.Reconfigurator;
import org.elasticsearch.cluster.coordination.StableMasterHealthIndicatorService;
import org.elasticsearch.cluster.desirednodes.DesiredNodesSettingsValidator;
import org.elasticsearch.cluster.metadata.IndexMetadataVerifier;
import org.elasticsearch.cluster.metadata.IndexTemplateMetadata;
import org.elasticsearch.cluster.metadata.Metadata;
import org.elasticsearch.cluster.metadata.MetadataCreateDataStreamService;
import org.elasticsearch.cluster.metadata.MetadataCreateIndexService;
import org.elasticsearch.cluster.metadata.MetadataDataStreamsService;
import org.elasticsearch.cluster.metadata.MetadataIndexTemplateService;
import org.elasticsearch.cluster.metadata.MetadataUpdateSettingsService;