SERVER-40792 Create error details if doesn't already exist when handling WouldChangeOwningShard error

1 files changed, 5 insertions, 1 deletions

diff --git a/src/mongo/s/commands/cluster_write_cmd.cpp b/src/mongo/s/commands/cluster_write_cmd.cpp
index b4b7660910c..5793d3a4d78 100644
--- a/src/mongo/s/commands/cluster_write_cmd.cpp
+++ b/src/mongo/s/commands/cluster_write_cmd.cpp
@@ -276,7 +276,11 @@ bool handleWouldChangeOwningShardError(OperationContext* opCtx,
                     "Update operation was converted into a distributed transaction because the "
                     "document being updated would move shards and that transaction failed");
             }
-
+            if (!response->isErrDetailsSet() || !response->getErrDetails().back()) {
+                auto error = stdx::make_unique<WriteErrorDetail>();
+                error->setIndex(0);
+                response->addToErrDetails(error.release());
+            }
             response->getErrDetails().back()->setStatus(status);
 
             auto txnRouterForAbort = TransactionRouter::get(opCtx);