diff --git a/app.py b/app.py
index ffc0bf7..7cdd6af 100644
--- a/app.py
+++ b/app.py
@@ -29,7 +29,7 @@ from ui_builder import install_ui_builder
 from khl_site.khl_data_center import APP as khl_site_app
 
 BASE_DIR = Path(__file__).resolve().parent
-BUILD_VERSION = "2026.09.15.5"
+BUILD_VERSION = "2026.09.15.6"
 # compatibility: BUILD_VERSION = "2026.08.26.1"
 # compatibility: BUILD_VERSION = "2026.08.25.1"
 # compatibility: BUILD_VERSION = "2026.08.24.15"
diff --git a/hockey_data/service.py b/hockey_data/service.py
index 00be047..3064c8e 100644
--- a/hockey_data/service.py
+++ b/hockey_data/service.py
@@ -867,6 +867,13 @@ class HockeyDataService:
         if row is None:
             row = Stadium(external_id=identity, source=str(source or "stat2tv")[:32], active=True)
             session.add(row)
+            # BUILD138: HockeyDatabase intentionally uses autoflush=False.
+            # Flush a newly created stadium immediately so another game in the
+            # same sync transaction can find the same external_id instead of
+            # creating a duplicate pending row and failing the UNIQUE constraint
+            # on commit. Stadium has no FK dependencies, so a targeted flush is
+            # safe and avoids flushing unrelated match-sync changes.
+            session.flush([row])
 
         manual = str(row.source or "").casefold() == "manual"
         for field, value in values.items():