SERVER-60869 Re-add logic to set feature compatibility version on arbiters

1 files changed, 9 insertions, 0 deletions

diff --git a/src/mongo/db/repl/replication_coordinator_impl.cpp b/src/mongo/db/repl/replication_coordinator_impl.cpp
index 87d8c31b5c4..c3c67f39cb2 100644
--- a/src/mongo/db/repl/replication_coordinator_impl.cpp
+++ b/src/mongo/db/repl/replication_coordinator_impl.cpp
@@ -4347,6 +4347,15 @@ ReplicationCoordinatorImpl::_updateMemberStateFromTopologyCoordinator(WithLock l
           "Replica set state transition",
           "newState"_attr = newState,
           "oldState"_attr = _memberState);
+
+    // Initializes the featureCompatibilityVersion to the latest value, because arbiters do not
+    // receive the replicated version. This is to avoid bugs like SERVER-32639.
+    if (newState.arbiter()) {
+        // (Generic FCV reference): This FCV check should exist across LTS binary versions.
+        serverGlobalParams.mutableFeatureCompatibility.setVersion(
+            multiversion::GenericFCV::kLatest);
+    }
+
     _memberState = newState;
 
     _cancelAndRescheduleElectionTimeout_inlock();