Windows: Cannot access samba share as Guest


since some later Versions of Windows 10 it is no longer possible to access Samba Public shares with Guest access as Windows User SYSTEM(i.e. from Schedule Tasks).

The error occured is:

The specified server cannot perform the requested operation.

Microsoft has limited the Guest Account in Windows 10 and connections with null sessions (User and Password are null) are prevented:

net use \\yourSambaServer\yourInsecureShare /user:"" ""
The specified server cannot perform the requested operation.

Windows resets the tcp session after the smb2 Sessions Setup Response of Samba:

Windows Guest Account Reset TCP Connection

Windows Guest Account Reset TCP Connection

In the samba log you find some strange errors like “smbd_change_to_root_user”, NT_STATUS_CONNECTION_RESET….

Two workarouds which brings back to old behaviour. Set the Samba max protocol to SMB1

        map to guest = Bad User
        guest account = nobody
        client min protocol  = nt1
        client max protocol  = nt1
        server max protocol  = nt1
        guest ok = yes

Or, the prefered way, set

reg add HKLM\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters /v AllowInsecureGuestAuth /d 1 /f /t REG_DWORD


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Add a comment »2 comments to this article

  1. The accepted answer works by lowering the security on the client side. It is not enforcing the restriction in Windows 10 / Windows Server which was added for security purposes. It requires adjusting each of your clients.

    On the other hand, the real answer is to raise the security on the server side and remove any mapping to guest accounts

    client min protocol = SMB3
    client max protocol = SMB3
    restrict anonymous = 2
    encrypt passwords = true

    – the `map to guest` option (which I had as bad user)
    – any ‘guest ok’ line in your smbd.conf

    restart samba and you’ll be prompted for a username/password instead.


    • Thanks Michael, that’s the better way to handle.


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