SERVER-26716 Fix crash after 3.2.old->3.2.new->3.2.old up/downgrader3.2.11-rc1

This was only an issue for nodes that had never done writes as a secondary
and therefore hadn't written a minValid point.

(cherry picked from commit 39d650faa5436a37359ca45717d5e988fb4461cb)

1 files changed, 4 insertions, 0 deletions

diff --git a/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp b/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp
index 67abc29502e..128e18b9f53 100644
--- a/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp
+++ b/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp
@@ -335,6 +335,10 @@ void ReplicationCoordinatorExternalStateImpl::cleanUpLastApplyBatch(OperationCon
         return;  // Initial Sync will take over so no cleanup is needed.
     }
 
+    // This initializes the minvalid document with a null "ts" because older versions (<3.2.10)
+    // get angry if the minValid document is present but doesn't have a "ts" field.
+    setMinValidToAtLeast(txn, {});
+
     const auto deleteFromPoint = getOplogDeleteFromPoint(txn);
     const auto appliedThrough = getAppliedThrough(txn);