How to fix Error 9750 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 9750 – Service Broker Routing Failure

Why This Error Happens

Error 9750 occurs when SQL Server’s Service Broker cannot locate a valid route for the destination service specified in a conversation, typically because the sys.routes catalog is missing an entry for that service name. This often happens after a database restore, migration, or mirroring failover where routing metadata wasn’t recreated, or when the service name in the BEGIN DIALOG statement doesn’t exactly match an existing route definition. It can also occur if the broker instance GUID changed (common after database copies) without updating the corresponding route’s BROKER_INSTANCE property.

Step-by-Step Resolution Guide

Step 1: Verify the Existing Routes and Services

  • Open SQL Server Management Studio (SSMS) and connect to the affected instance.
  • Run the following query to inspect current routing configuration:
SELECT * FROM sys.routes;
SELECT * FROM sys.services;
  • Confirm whether a route exists for the destination service name referenced in your error message.

Step 2: Create or Correct the Missing Route

  • If no route exists, create one using CREATE ROUTE, specifying the exact service name and address:
CREATE ROUTE RouteToTargetService
    AUTHORIZATION dbo
    WITH SERVICE_NAME = 'TargetServiceName',
    ADDRESS = 'TCP://TargetServerName:4022';
  • If the route exists but points to an outdated broker instance, drop and recreate it:
DROP ROUTE RouteToTargetService;
CREATE ROUTE RouteToTargetService
    WITH SERVICE_NAME = 'TargetServiceName',
    ADDRESS = 'TCP://TargetServerName:4022',
    BROKER_INSTANCE = 'NewBrokerInstanceGUID';
  • Retrieve the correct BROKER_INSTANCE GUID by running SELECT service_broker_guid FROM sys.databases WHERE name = 'YourDatabaseName'; on the target server.

Step 3: Check Firewall and Endpoint Configuration on Windows Server 2025

  • Ensure the Service Broker endpoint (default port 4022) is enabled:
SELECT * FROM sys.tcp_endpoints WHERE type_desc = 'SERVICE_BROKER';
  • In Windows Defender Firewall (Control Panel > System and Security > Windows Defender Firewall > Advanced Settings), add an inbound rule allowing TCP port 4022.
  • Restart the SQL Server service via services.msc or run net stop MSSQLSERVER && net start MSSQLSERVER in an elevated Command Prompt to apply endpoint changes.

Step 4: Validate Conversation Priority and Contract Bindings

  • Confirm the contract and message types referenced in the conversation match those defined on both the initiator and target services.
  • Re-send a test message using BEGIN DIALOG CONVERSATION and SEND ON CONVERSATION to confirm the route resolves without triggering Error 9750 again.

Alternative or Verification Steps

  • Query sys.transmission_queue on the initiating database; if the row referencing your conversation handle disappears after creating the route, the message was delivered successfully.
  • As an alternative, enable Service Broker diagnostic trace flags (such as 9984 for extended broker logging) temporarily to capture deeper routing failure details if the issue persists after recreating routes.