diff --git a/firestore-bigquery-export/firestore-bigquery-change-tracker/src/bigquery/checkUpdates.ts b/firestore-bigquery-export/firestore-bigquery-change-tracker/src/bigquery/checkUpdates.ts
index 6313f32cc..e18af3d14 100644
--- a/firestore-bigquery-export/firestore-bigquery-change-tracker/src/bigquery/checkUpdates.ts
+++ b/firestore-bigquery-export/firestore-bigquery-change-tracker/src/bigquery/checkUpdates.ts
@@ -23,7 +23,7 @@ export async function tableRequiresUpdate({
   const { metadata } = table;
 
   /** Check clustering */
-  const configCluster = JSON.stringify(config.clustering);
+  const configCluster = JSON.stringify(config.clustering || []);
   const tableCluster = JSON.stringify(metadata.clustering?.fields || []);
   if (configCluster !== tableCluster) return true;
 
diff --git a/firestore-bigquery-export/firestore-bigquery-change-tracker/src/bigquery/handleFailedTransactions.ts b/firestore-bigquery-export/firestore-bigquery-change-tracker/src/bigquery/handleFailedTransactions.ts
index 4addaeec9..5bf894430 100644
--- a/firestore-bigquery-export/firestore-bigquery-change-tracker/src/bigquery/handleFailedTransactions.ts
+++ b/firestore-bigquery-export/firestore-bigquery-change-tracker/src/bigquery/handleFailedTransactions.ts
@@ -7,15 +7,30 @@ if (!admin.apps.length) {
   initializeApp();
 }
 
+const settingsApplied = new Set<string | undefined>();
+
+const getConfiguredFirestore = (instanceId?: string) => {
+  const db = instanceId ? getFirestore(instanceId) : getFirestore();
+  if (!settingsApplied.has(instanceId)) {
+    settingsApplied.add(instanceId);
+    try {
+      db.settings({ ignoreUndefinedProperties: true });
+    } catch {
+      // Firestore.settings() throws if the singleton has already been used
+      // elsewhere in the process. The dead-letter path doesn't strictly
+      // depend on ignoreUndefinedProperties, so swallow rather than crash
+      // and mask the original BigQuery error that led us here.
+    }
+  }
+  return db;
+};
+
 export default async (
   rows: any[],
   config: ChangeTrackerConfig,
   e: Error
 ): Promise<void> => {
-  const db = getFirestore(config.firestoreInstanceId!);
-  db.settings({
-    ignoreUndefinedProperties: true,
-  });
+  const db = getConfiguredFirestore(config.firestoreInstanceId);
   const batchArray = [db.batch()];
 
   let operationCounter = 0;
diff --git a/firestore-bigquery-export/firestore-bigquery-change-tracker/src/bigquery/index.ts b/firestore-bigquery-export/firestore-bigquery-change-tracker/src/bigquery/index.ts
index 7b6f8a15e..f6202970e 100644
--- a/firestore-bigquery-export/firestore-bigquery-change-tracker/src/bigquery/index.ts
+++ b/firestore-bigquery-export/firestore-bigquery-change-tracker/src/bigquery/index.ts
@@ -341,14 +341,14 @@ export class FirestoreBigQueryEventHistoryTracker
 
       await clustering.updateClustering(metadata);
 
-      const documentIdColExists = fields.find(
+      const documentIdColExists = fields.some(
         (column) => column.name === "document_id"
       );
-      const pathParamsColExists = fields.find(
+      const pathParamsColExists = fields.some(
         (column) => column.name === "path_params"
       );
 
-      const oldDataColExists = fields.find(
+      const oldDataColExists = fields.some(
         (column) => column.name === "old_data"
       );