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Shared Folder Not Accessible After Windows 10 Update

Starting with Windows 10 build 21H2, users began to complain that when they tried to open a network shared folder on a neighboring computer, an error appeared:

Restoring Network Connections
An error occurs when you try to open a network folder:
An error occurred while reconnecting Y: to \\nas1\share
Microsoft Windows Network: You can’t access this shared folder because your organization’s security policies block unauthenticated guest access. These policies help protect your PC from unsafe or malicious devices on the network.

I have also seen other various error messages, depending on the OS version of the client.

I have even seen a Windows 10 host computer not appear on NETWORK until both the host and client had version 21H2 installed.


To enable guest access from your computer, you need to use the Group Policy Editor (gpedit.msc). Go to the section: Computer Configuration -> Administrative templates -> Network -> Lanman Workstation. Find and enable the policy Enable insecure guest logons. This policy option determines whether the SMB client will allow an unsafe guest logon to the SMB server.

Update the Group Policy settings in Windows with the command:

gpupdate /force

Or you can make a similar change through the Registry Editor manually:

HKLM\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters “AllowInsecureGuestAuth”=dword:1