1 files changed, 2 insertions, 0 deletions
diff --git a/src/mongo/db/pipeline/document_source_internal_unpack_bucket.h b/src/mongo/db/pipeline/document_source_internal_unpack_bucket.h
index 7ec99287ebc..7d3be11e85e 100644
--- a/src/mongo/db/pipeline/document_source_internal_unpack_bucket.h
+++ b/src/mongo/db/pipeline/document_source_internal_unpack_bucket.h
@@ -105,6 +105,8 @@ public:
                                      UnionRequirement::kAllowed,
                                      ChangeStreamRequirement::kDenylist};
         constraints.canSwapWithMatch = true;
+        // The user cannot specify multiple $unpackBucket stages in the pipeline.
+        constraints.canAppearOnlyOnceInPipeline = true;
         return constraints;
     }