How to fix Error 9753 on Windows Server 2025 / Windows 11

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Why This Error Happens

Error 9753 occurs when the Service Broker endpoint on the target SQL Server instance cannot be reached over the network, typically due to the TCP endpoint being disabled, stopped, or blocked by a firewall. This can also happen if the Service Broker GUID in the routing information is mismatched after a database restore, or if the SQL Server Browser service and port configuration are not aligned between the initiator and target instances. Certificate or authentication failures during the Service Broker handshake can also cause the endpoint to appear unreachable.

Step-by-Step Resolution Guide

Step 1: Verify the Service Broker Endpoint Is Enabled

  • Run SELECT * FROM sys.service_broker_endpoints; on the target instance to confirm the endpoint exists and state_desc shows STARTED.
  • If stopped, run ALTER ENDPOINT [Broker_Endpoint] STATE = STARTED;.
  • Confirm the endpoint is listening on the expected TCP port (default 4022) using netstat -ano | findstr 4022 in an elevated Command Prompt.

Step 2: Check Windows Firewall and Network Path

  • Open Windows Defender Firewall with Advanced Security on Windows Server 2025 and confirm an inbound rule exists for TCP port 4022.
  • If missing, create one: New-NetFirewallRule -DisplayName "SQL Server Service Broker" -Direction Inbound -Protocol TCP -LocalPort 4022 -Action Allow in PowerShell (run as Administrator).
  • Test connectivity from the initiator server using Test-NetConnection -ComputerName <TargetServerName> -Port 4022.

Step 3: Validate Routing and Broker Identifiers

  • Query SELECT * FROM sys.routes; on both the initiator and target databases to ensure the address and broker_instance values match the actual Service Broker GUID (SELECT service_broker_guid FROM sys.databases WHERE name = 'YourDB';).
  • If the database was restored or copied, recreate the route with the correct GUID using ALTER ROUTE.
  • Ensure the ADDRESS in the route points to the correct hostname/IP and port (e.g., TCP://TargetServer:4022).

Step 4: Review Certificate and Authentication Settings

  • If using certificate-based authentication, confirm certificates haven’t expired by checking SELECT name, expiry_date FROM sys.certificates; on both instances.
  • Re-export and re-import the public key certificates between initiator and target if a mismatch is found.
  • Restart the SQL Server service (services.msc or Restart-Service MSSQLSERVER) after certificate updates to apply changes.

Alternative or Verification Steps

  • Run SELECT * FROM sys.transmission_queue; on the initiator to confirm the transmission_status column no longer shows the 9753 error message after applying fixes.
  • If the issue persists, temporarily use NET.TCP:: loopback testing on the same server to isolate whether the issue is network-based or configuration-based within SQL Server itself.