How to fix Error 1272 on Windows 11

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Windows 11 Troubleshooting Guide: Error 1272 – Unauthenticated Guest Access Blocked

Why This Error Happens

This error occurs because Windows 11 disables the “Insecure Guest Logons” policy by default as a security hardening measure against SMBv2/SMBv3 vulnerabilities. The client PC is attempting to connect to a shared folder hosted on a device (often an older NAS, router, or a non-domain Windows machine) that only supports guest/anonymous authentication rather than requiring valid credentials. Since Windows 11 blocks any SMB connection that isn’t properly authenticated, the connection is refused with Error 1272 to prevent exposure to unsafe network devices.

Step-by-Step Resolution Guide

  1. Verify the source of the problem: Confirm the shared folder is hosted on a device that doesn’t support authenticated logins (e.g., an older NAS or router). If possible, the better long-term fix is to update that device’s firmware or configure it to require a username/password rather than allowing guest access.

  2. Enable Insecure Guest Logons via Local Group Policy Editor:

  • Press Win + R, type gpedit.msc, and press Enter.
  • Navigate to: Computer Configuration > Administrative Templates > Network > Lanman Workstation.
  • Locate “Enable insecure guest logons”, double-click it, select Enabled, click Apply, then OK.
  1. Restart the Workstation service to apply changes without a full reboot:
  • Open Command Prompt as Administrator.
  • Run: net stop LanmanWorkstation followed by net start LanmanWorkstation.
  • Alternatively, restart the PC to ensure the policy takes effect.
  1. If Group Policy Editor is unavailable (Windows 11 Home), apply the same setting via Registry Editor:
  • Press Win + R, type regedit, and press Enter.
  • Navigate to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters.
  • Create a new DWORD (32-bit) Value named AllowInsecureGuestAuth, set its value to 1.
  • Restart the PC.
  1. Attempt to reconnect to the shared folder using File Explorer (\\ServerName\ShareName) and confirm access is restored.

Alternative or Verification Steps

  • Verify the fix: Open File Explorer, type the network path in the address bar, and confirm the folder opens without the Error 1272 prompt. Check Event Viewer under Windows Logs > System for any recurring SMB-related warnings.
  • Safer alternative: Instead of enabling insecure guest logons system-wide, ask the shared folder’s administrator to set up a proper user account with a password on the hosting device — this avoids weakening your PC’s security posture while still resolving access.