Symptom:

When user tries to access the Share from Windows Explorer, they get the following error without receiving a prompt to enter their credentials:



Cause:

In Windows 10 and Windows Server 2022, there is a registry key that disables guest access on SMB2 called "AllowInsecureGuestAuth". By default, this key is set to 0.


The key is located at: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters


This feature is by designed and recommended by Microsoft for security purposes.


Resolution:

Any of the Guidances listed below will resolve the issue to access the network share.


Guidance 1: 

Make sure the username used to log in to the Windows client exists in the Morro Data system. The username can be either a network username for User Mode or Active Directory Mode or the email address in Office365 of Azure for Azure AD Mode. If the usernames exist in the Morro Data system, the user will be shown the prompt to enter their credentials.


Guidance 2:

Change the AllowInsecureGuestAuth value to 1 to enable guest access to SMB2 shares.

  1. Open the Registry editor by running the command 'regedit' from the run menu.

  2. Browse to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters

  3. Find the key AllowInsecureGuestAuth and change the value to 1.


Guidance 3:

Remove the key "AllowInsecureGuestAuth"

  1. Open the Registry editor by running the command 'regedit' from the run menu.

  2. Browse to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters

  3. Find the key AllowInsecureGuestAuth.

  4. Right click the key and choose Delete.

 

Guidance 4:

Change the following Group Policy setting to enable insecure guest access:

  1. Open the Local Group Policy editor
  2. Go to Computer Configuration\Administrative Templates\Network\Lanman Workstation
  3. For the setting, "Enable insecure guest logons" right click and choose Edit.
  4. Choose "Enabled" and click OK



More Information:

The issue is related to Windows 10 and Windows Server version 1709. In Windows 10 version 1803, the key does not exist.


For additional information, please refer to the support article from Microsoft: Guest access in SMB2 disabled by default in Windows 10 Fall Creators Update and Windows Server 2016 version 1709