1 files changed, 18 insertions, 49 deletions
diff --git a/src/mongo/db/repl/replication_coordinator_impl.cpp b/src/mongo/db/repl/replication_coordinator_impl.cpp
index f63f9b90ece..69b769e0cc6 100644
--- a/src/mongo/db/repl/replication_coordinator_impl.cpp
+++ b/src/mongo/db/repl/replication_coordinator_impl.cpp
@@ -3467,57 +3467,26 @@ Status ReplicationCoordinatorImpl::_doReplSetReconfig(OperationContext* opCtx,
         return status;
     ReplSetConfig newConfig = newConfigStatus.getValue();
 
-    // Excluding reconfigs that bump the config term during step-up from checking against changing
-    // the implicit default write concern, as it is not needed.
-    if (!skipSafetyChecks /* skipping step-up reconfig */) {
+    // If the new config changes the replica set's implicit default write concern, we fail the
+    // reconfig command. This includes force reconfigs, but excludes reconfigs that bump the config
+    // term during step-up. The user should set a cluster-wide write concern and attempt the
+    // reconfig command again. We also need to exclude shard servers from this validation, as shard
+    // servers don't store the cluster-wide write concern.
+    if (!skipSafetyChecks /* skipping step-up reconfig */ &&
+        repl::feature_flags::gDefaultWCMajority.isEnabled(
+            serverGlobalParams.featureCompatibility) &&
+        serverGlobalParams.clusterRole != ClusterRole::ShardServer &&
+        !repl::enableDefaultWriteConcernUpdatesForInitiate.load()) {
         bool currIDWC = oldConfig.isImplicitDefaultWriteConcernMajority();
         bool newIDWC = newConfig.isImplicitDefaultWriteConcernMajority();
-
-        // If the new config changes the replica set's implicit default write concern, we fail the
-        // reconfig command. This includes force reconfigs.
-        // The user should set a cluster-wide write concern and attempt the reconfig command again.
-        if (serverGlobalParams.clusterRole != ClusterRole::ShardServer) {
-            if (repl::feature_flags::gDefaultWCMajority.isEnabled(
-                    serverGlobalParams.featureCompatibility) &&
-                !repl::enableDefaultWriteConcernUpdatesForInitiate.load() && currIDWC != newIDWC &&
-                !ReadWriteConcernDefaults::get(opCtx).isCWWCSet(opCtx)) {
-                return Status(
-                    ErrorCodes::NewReplicaSetConfigurationIncompatible,
-                    str::stream()
-                        << "Reconfig attempted to install a config that would change the implicit "
-                           "default write concern. Use the setDefaultRWConcern command to set a "
-                           "cluster-wide write concern and try the reconfig again.");
-            }
-        } else {
-            // Allow all reconfigs if the shard is not part of a sharded cluster yet, however
-            // prevent changing the implicit default write concern to (w: 1) after it becomes part
-            // of a sharded cluster and CWWC is not set on the cluster.
-            // Remote call to the configServer should be done to check if CWWC is set on the
-            // cluster.
-            if (_externalState->isShardPartOfShardedCluster(opCtx) && currIDWC != newIDWC &&
-                !newIDWC) {
-                try {
-                    // Initiates a remote call to the config server.
-                    if (!_externalState->isCWWCSetOnConfigShard(opCtx)) {
-                        return Status(
-                            ErrorCodes::NewReplicaSetConfigurationIncompatible,
-                            str::stream()
-                                << "Reconfig attempted to install a config that would change the "
-                                   "implicit default write concern on the shard to {w: 1}. Use the "
-                                   "setDefaultRWConcern command to set a cluster-wide write "
-                                   "concern on the cluster and try the reconfig again.");
-                    }
-                } catch (const DBException& ex) {
-                    return Status(
-                        ErrorCodes::ConfigServerUnreachable,
-                        str::stream()
-                            << "Reconfig attempted to install a config that would change the "
-                               "implicit default write concern on the shard to {w: 1}, but the "
-                               "shard can not check if CWWC is set on the cluster, as the request "
-                               "to the config server is failing with error: " +
-                                ex.toString());
-                }
-            }
+        bool isCWWCSet = ReadWriteConcernDefaults::get(opCtx).isCWWCSet(opCtx);
+        if (!isCWWCSet && currIDWC != newIDWC) {
+            return Status(
+                ErrorCodes::NewReplicaSetConfigurationIncompatible,
+                str::stream()
+                    << "Reconfig attempted to install a config that would change the "
+                       "implicit default write concern. Use the setDefaultRWConcern command to "
+                       "set a cluster-wide write concern and try the reconfig again.");
         }
     }