How to fix Error 11280 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 11280 – Packet Exceeds Receive Buffer Count

Why This Error Happens

This error occurs when SQL Server’s Tabular Data Stream (TDS) receives a network packet larger than the buffer size it has been configured to accept, typically due to a mismatch between client and server packet size settings. It can also result from network interface misconfigurations, outdated network drivers, or corrupted TDS endpoint configurations on the SQL Server instance. In some cases, aggressive third-party firewall or antivirus packet inspection tools interfere with packet fragmentation, causing oversized packets to reach the server unprocessed.

Step-by-Step Resolution Guide

Step 1: Verify and Adjust the Network Packet Size Configuration

  • Open SQL Server Management Studio (SSMS) and connect to the instance.
  • Run EXEC sp_configure 'network packet size'; to check the current configured value.
  • If the value exceeds 4096 bytes (default) without justification, reset it using: EXEC sp_configure 'network packet size', 4096; RECONFIGURE;
  • Restart the SQL Server service via services.msc or Restart-Service MSSQLSERVER in PowerShell.

Step 2: Inspect and Reset the TDS Endpoint Settings

  • Open SQL Server Configuration Manager (found under Start > Microsoft SQL Server 2025 Tools).
  • Navigate to SQL Server Network Configuration > Protocols for [Instance Name].
  • Right-click TCP/IP, select Properties, and confirm the IP All section has standard port settings (default 1433) without manual overrides causing buffer mismatches.
  • Disable and re-enable the TCP/IP protocol to force a clean reload, then restart the SQL Server service.

Step 3: Update Network Drivers and Check MTU Settings

  • On Windows Server 2025 / Windows 11, go to Device Manager > Network Adapters, right-click the active adapter, and select Update Driver.
  • Open PowerShell as Administrator and run netsh interface ipv4 show subinterfaces to check the current MTU size.
  • Ensure MTU is consistent across client and server (commonly 1500); adjust using netsh interface ipv4 set subinterface "Ethernet" mtu=1500 store=persistent if there’s a mismatch.

Step 4: Review Firewall and Antivirus Packet Inspection Rules

  • Open Windows Defender Firewall with Advanced Security and check inbound rules for SQL Server (port 1433 and relevant dynamic ports).
  • Temporarily disable third-party antivirus/firewall deep packet inspection features to test if they are fragmenting or blocking large packets incorrectly.
  • Re-enable protections once confirmed, adding explicit exceptions for sqlservr.exe if needed.

Alternative or Verification Steps

  • To verify the fix, generate a test query with a large result set (e.g., bulk insert or large SELECT with string concatenation) and confirm it completes without triggering Error 11280 in the SQL Server Error Log (Management > SQL Server Logs in SSMS).
  • If the issue persists, consider rebuilding the SQL Server network library configuration by uninstalling and reinstalling the Database Engine Services feature via SQL Server Installation Center, ensuring no corrupted binaries are causing the buffer limitation.