⚠️ 2 verified solutions available for Error 1937 — Last updated 2026-03-13
Error 1937 📋

Fix ERROR_NTLM_BLOCKED — Windows Error Code 1937

Error 1937 (ERROR_NTLM_BLOCKED) is a Windows RPC & Network error that occurs when authentication failed because ntlm authentication has been disabled.. This guide provides step-by-step solutions to resolve this issue.

🏷️ Code: 1937 📛 ERROR_NTLM_BLOCKED 📅 Updated: 2026-03-13 ⏱️ 2 Solutions

🎮 Common Scenario: Are you experiencing Error 1937 while launching or installing Valorant? The solutions below directly address the system interactions specific to this application.

⚡ Quick Fix

Reset Network Stack: Open Command Prompt as Administrator

👇 See all 2 solutions below

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📑 Table of Contents
What is Error 1937? Common Causes Step-by-Step Solutions Prevention Tips Related Errors

💡 What is Error 1937?

Windows System Error Code 1937, known as ERROR_NTLM_BLOCKED, is a RPC & Network error that occurs during Remote Procedure Call (RPC) and network communication. The error indicates that: Authentication failed because NTLM authentication has been disabled. When this error is encountered, the Windows operating system was unable to complete the requested operation within the network services subsystem. The error code 1937 is returned by the GetLastError() function and provides developers with a specific identifier to diagnose the root cause of the failure. The symbolic name ERROR_NTLM_BLOCKED maps directly to this numeric code and is commonly referenced in Microsoft documentation, developer forums, and system logs. Understanding this error and its context within Remote Procedure Call (RPC) and network communication is essential for effective troubleshooting.

⚠️ Common Causes

  • RPC server is unavailable
  • Network connectivity issues
  • Firewall blocking required ports
  • Remote endpoint timeout
📚 Comprehensive Guide

Troubleshooting COM and DCOM Architectural Failures (Event ID 10016)

A comprehensive guide on Component Object Model (COM), Distributed COM (DCOM), and how to safely interpret and resolve Event ID 10016 errors.

Read the full guide →

✅ Step-by-Step Solutions

1 Reset Network Stack
  1. Open Command Prompt as Administrator
  2. Run: netsh winsock reset
  3. Run: netsh int ip reset
  4. Run: ipconfig /flushdns
  5. Restart your computer
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2 Check RPC Service
  1. Open services.msc
  2. Ensure 'Remote Procedure Call (RPC)' is Running and Automatic
  3. Also check 'DCOM Server Process Launcher'
  4. Restart both if stopped

🎬 Video Tutorials

▶️ Watch Video Tutorials
How To Fix Windows Firewall Blocking Error
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💻 Diagnostic Command

Run this PowerShell command to find related events in your system log:

Get-EventLog -LogName System -Newest 20 | Where-Object {$_.Message -like "*1937*" -or $_.Message -like "*ERROR_NTLM_BLOCKED*"} | Format-List

💡 Open PowerShell as Administrator, paste the command above, and press Enter.

🛡️ Prevention Tips

  • Monitor network health regularly
  • Document firewall rules
  • Test connectivity after infrastructure changes
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Last updated: 2026-03-13
📖
Based on Official Microsoft Documentation
Solutions Tested on Windows 10 & 11
Error codes sourced from Microsoft Win32 SDK. Updated 2026-03-13.
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