diff --git a/src/main/java/com/iemr/flw/domain/iemr/DiagnosticDocument.java b/src/main/java/com/iemr/flw/domain/iemr/DiagnosticDocument.java
index d4e78747..5afd367a 100644
--- a/src/main/java/com/iemr/flw/domain/iemr/DiagnosticDocument.java
+++ b/src/main/java/com/iemr/flw/domain/iemr/DiagnosticDocument.java
@@ -84,6 +84,6 @@ public class DiagnosticDocument {
     @Column(name = "parkingPlaceID")
     private Integer parkingPlaceID;
 
-    @Column(name = "vanSerialNo")
+    @Column(name = "vanSerialNo", updatable = false)
     private Long vanSerialNo;
 }
\ No newline at end of file
diff --git a/src/main/java/com/iemr/flw/domain/iemr/DiagnosticOrder.java b/src/main/java/com/iemr/flw/domain/iemr/DiagnosticOrder.java
index 197999fe..aa89012e 100644
--- a/src/main/java/com/iemr/flw/domain/iemr/DiagnosticOrder.java
+++ b/src/main/java/com/iemr/flw/domain/iemr/DiagnosticOrder.java
@@ -101,6 +101,6 @@ public class DiagnosticOrder {
     @Column(name = "processed")
     private String processed = "N";
 
-    @Column(name = "vanSerialNo")
+    @Column(name = "vanSerialNo", updatable = false)
     private Long vanSerialNo;
 }
diff --git a/src/main/java/com/iemr/flw/domain/iemr/DiagnosticProviderToken.java b/src/main/java/com/iemr/flw/domain/iemr/DiagnosticProviderToken.java
index 8ef23306..da8e23dd 100644
--- a/src/main/java/com/iemr/flw/domain/iemr/DiagnosticProviderToken.java
+++ b/src/main/java/com/iemr/flw/domain/iemr/DiagnosticProviderToken.java
@@ -46,6 +46,6 @@ public class DiagnosticProviderToken {
     @Column(name = "parkingPlaceID")
     private Integer parkingPlaceID;
 
-    @Column(name = "vanSerialNo")
+    @Column(name = "vanSerialNo", updatable = false)
     private Long vanSerialNo;
 }
diff --git a/src/main/java/com/iemr/flw/domain/iemr/DiagnosticResult.java b/src/main/java/com/iemr/flw/domain/iemr/DiagnosticResult.java
index 6cb9fba6..55bce475 100644
--- a/src/main/java/com/iemr/flw/domain/iemr/DiagnosticResult.java
+++ b/src/main/java/com/iemr/flw/domain/iemr/DiagnosticResult.java
@@ -70,6 +70,6 @@ public class DiagnosticResult {
     @Column(name = "parkingPlaceID")
     private Integer parkingPlaceID;
 
-    @Column(name = "vanSerialNo")
+    @Column(name = "vanSerialNo", updatable = false)
     private Long vanSerialNo;
 }
diff --git a/src/main/java/com/iemr/flw/domain/iemr/StopTBDiagnostics.java b/src/main/java/com/iemr/flw/domain/iemr/StopTBDiagnostics.java
index f9abde57..e81b553d 100644
--- a/src/main/java/com/iemr/flw/domain/iemr/StopTBDiagnostics.java
+++ b/src/main/java/com/iemr/flw/domain/iemr/StopTBDiagnostics.java
@@ -135,6 +135,6 @@ public class StopTBDiagnostics {
     @Column(name = "processed")
     private String processed = "N";
 
-    @Column(name = "vanSerialNo")
+    @Column(name = "vanSerialNo", updatable = false)
     private Long vanSerialNo;
 }
diff --git a/src/main/java/com/iemr/flw/service/impl/DiagnosticOrderServiceImpl.java b/src/main/java/com/iemr/flw/service/impl/DiagnosticOrderServiceImpl.java
index 3e5ca60d..d8dfc6ab 100644
--- a/src/main/java/com/iemr/flw/service/impl/DiagnosticOrderServiceImpl.java
+++ b/src/main/java/com/iemr/flw/service/impl/DiagnosticOrderServiceImpl.java
@@ -136,6 +136,11 @@ public DiagnosticOrder createAndPushOrder(DiagnosticOrderRequestDto request) thr
             }
             throw dive;
         }
+        // Stamp the sync key before the (possibly slow) vendor push, so a crash/restart mid-push can't leave it NULL.
+        if (order.getVanSerialNo() == null) {
+            diagnosticOrderRepo.updateVanSerialNo(order.getId());
+            order.setVanSerialNo(order.getId());
+        }
 
         if (providerCode == null || providerCode.isBlank()) {
             logger.info("No active vendor configured for orderType={}, beneficiaryId={} — order saved for manual entry",
@@ -338,7 +343,9 @@ public DiagnosticPollResult pollOnce(DiagnosticOrder order) throws Exception {
             order.setStatus(DiagnosticOrderStatus.FAILED.name());
             order.setErrorMessage("No push response recorded for this order — cannot poll");
             order.setLastPolledAt(new Timestamp(System.currentTimeMillis()));
-            diagnosticOrderRepo.save(order);
+            order = diagnosticOrderRepo.save(order);
+            // The scheduler's copy may predate createAndPushOrder's updateVanSerialNo(); fill it if still missing.
+            if (order.getVanSerialNo() == null) diagnosticOrderRepo.updateVanSerialNo(order.getId());
             return null;
         }
         DiagnosticProvider provider = providerFactory.getProvider(order.getProviderCode());