diff --git a/server/src/queue/blueGreen/blueGreenReadinessChecks.ts b/server/src/queue/blueGreen/blueGreenReadinessChecks.ts
index f9a827e2b..fb4174b28 100644
--- a/server/src/queue/blueGreen/blueGreenReadinessChecks.ts
+++ b/server/src/queue/blueGreen/blueGreenReadinessChecks.ts
@@ -1,9 +1,13 @@
-import { GetQueueAttributesCommand, type SQSClient } from "@aws-sdk/client-sqs";
+import { GetQueueAttributesCommand, SQSClient } from "@aws-sdk/client-sqs";
 import type { DrizzleCli } from "@/db/initDrizzle.js";
+import {
+	DEFAULT_AWS_REGION,
+	extractRegionFromQueueUrl,
+} from "@/external/aws/awsRegionUtils.js";
 import { redis } from "@/external/redis/initRedis.js";
 import { resolveRedisV2 } from "@/external/redis/resolveRedisV2.js";
 import { withTimeout } from "@/utils/withTimeout.js";
-import { getSqsClient, QUEUE_URL } from "../initSqs.js";
+import { QUEUE_URL } from "../initSqs.js";
 import type { BlueGreenProbeResult } from "./blueGreenSchemas.js";
 
 const CHECK_TIMEOUT_MS = 5_000;
@@ -41,6 +45,7 @@ const getConfiguredQueueUrls = () =>
 		QUEUE_URL,
 		process.env.TRACK_SQS_QUEUE_URL,
 		process.env.SQS_QUEUE_URL,
+		process.env.SQS_QUEUE_URL_V2,
 	].filter((url): url is string => Boolean(url));
 
 export const getBlueGreenQueueUrls = ({
@@ -50,13 +55,27 @@ export const getBlueGreenQueueUrls = ({
 } = {}) =>
 	Array.from(new Set([...getConfiguredQueueUrls(), ...knownQueueUrls]));
 
+// Build a per-queue-URL SQSClient using the region extracted from the URL,
+// so SigV4 signs against the queue's region. Reusing one singleton across
+// queues in different regions fails with "Credential should be scoped to a
+// valid region" because the client's region disagrees with the endpoint
+// the SDK falls back to (the queue URL's host).
+const sqsClientsByRegion = new Map<string, SQSClient>();
+const getSqsClientForQueue = (queueUrl: string): SQSClient => {
+	const region =
+		extractRegionFromQueueUrl({ queueUrl }) ?? DEFAULT_AWS_REGION;
+	const cached = sqsClientsByRegion.get(region);
+	if (cached) return cached;
+	const client = new SQSClient({ region });
+	sqsClientsByRegion.set(region, client);
+	return client;
+};
+
 export const runBlueGreenReadinessChecks = async ({
 	db,
-	sqs = getSqsClient(),
 	queueUrls = getBlueGreenQueueUrls(),
 }: {
 	db: DrizzleCli;
-	sqs?: SQSClient;
 	queueUrls?: string[];
 }) => {
 	const [dbCheck, redisCheck, redisV2Check, sqsCheck] = await Promise.all([
@@ -82,7 +101,7 @@ export const runBlueGreenReadinessChecks = async ({
 				}
 				await Promise.all(
 					queueUrls.map((queueUrl) =>
-						sqs.send(
+						getSqsClientForQueue(queueUrl).send(
 							new GetQueueAttributesCommand({
 								QueueUrl: queueUrl,
 								AttributeNames: ["ApproximateNumberOfMessages"],