diff --git a/src/mongo/db/query/query_feature_flags.idl b/src/mongo/db/query/query_feature_flags.idl
index 4ad720b5da..45202304db 100644
--- a/src/mongo/db/query/query_feature_flags.idl
+++ b/src/mongo/db/query/query_feature_flags.idl
@@ -39,7 +39,8 @@ feature_flags:
         description: >-
           When set to true, SBE engine is used instead of the classic engine.
         cpp_varname: gSBE
-        default: false
+        version: 4.9
+        default: true
 
     featureFlagChangeStreamsOptimization:
       description: "Feature flag for enabling change streams optimization"
diff --git a/src/mongo/db/query/sbe_stage_builder.cpp b/src/mongo/db/query/sbe_stage_builder.cpp
index 1634bda401..35aca879c0 100644
--- a/src/mongo/db/query/sbe_stage_builder.cpp
+++ b/src/mongo/db/query/sbe_stage_builder.cpp
@@ -1845,6 +1845,11 @@ std::pair<std::unique_ptr<sbe::PlanStage>, PlanStageSlots> SlotBasedStageBuilder
             {STAGE_SORT_MERGE, &SlotBasedStageBuilder::buildSortMerge},
             {STAGE_SHARDING_FILTER, &SlotBasedStageBuilder::buildShardFilter}};
 
+    auto supported = kStageBuilders.find(root->getType()) != kStageBuilders.end();
+    if (!supported) {
+      std::cout << "Node " << root->toString() << std::endl;
+      invariant(false);
+    }
     tassert(4822884,
             str::stream() << "Unsupported QSN in SBE stage builder: " << root->toString(),
             kStageBuilders.find(root->getType()) != kStageBuilders.end());