“Your organization’s security policies block unauthenticated guest access”: fix

Why Windows blocks the share

The full message reads: 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. It usually appears when you open a NAS, a router’s USB storage or a Samba share that lets anyone in without a password.

Two separate Windows changes cause it, according to Microsoft’s documentation:

• Insecure guest logons are off by default. Since Windows 10 version 1709, the SMB client won’t use guest access on Windows 10 Enterprise, Education and Pro for Workstations. Windows 11 Pro joined them from Insider build 25267, so in practice from version 24H2. Windows 10 Home and Pro still allow guest access.
• SMB signing is required in Windows 11 24H2. Microsoft says 24H2 Pro, Enterprise and Education require SMB signing, and that requiring signing also disables guest access. That’s why some people still get the error after enabling guest logons. Windows 11 24H2 Home doesn’t require signing.

Microsoft’s reasoning is that a guest connection has no identity check, so a fake server on the network could feed you malicious files without any password prompt.

Check what your PC enforces

Open Terminal or PowerShell and run:

Get-SmbClientConfiguration | Format-List EnableInsecureGuestLogons,RequireSecuritySignature

EnableInsecureGuestLogons : False means guest access is blocked. RequireSecuritySignature : True means signing is required, which blocks guest access too. On Windows 11 24H2 you can also open Event Viewer and look under Applications and Services Logs > Microsoft > Windows > SMBClient > Security for event 31017, which Microsoft documents as a rejected insecure guest logon.

Best fix: give the share a username and password

Microsoft’s recommended order is to turn on a username and password on the NAS (and SMB signing there if it offers it), then update its firmware, and only replace the device as a last resort. With a real account, Windows doesn’t need any security setting lowered.

1. In the NAS or router’s admin page, create a user, give it a password and grant it access to the shared folder. Turn off guest or anonymous access for that share if the option exists.
2. On the PC, open File Explorer, right-click This PC and choose Map network drive (on Windows 11 it may be under Show more options).
3. Enter the share path, such as \\NAS\Media, tick Connect using different credentials and select Finish.
4. Type the NAS username and password and tick Remember my credentials. Windows stores them in Credential Manager.

From a command prompt, the same mapping looks like this; Windows prompts for the password:

net use Z: \\NAS\Media /user:nasuser /persistent:yes

If the share is on another Windows PC, use an account that exists on that PC. Our guide on how to map a network drive covers the options in more detail.

Workaround on Pro, Enterprise and Education

Before you start: Microsoft says enabling guest logons and turning off signing can expose the PC to spoofed servers, ransomware delivered through the share and man-in-the-middle attacks. Only do this on a private home or office network, for a device you can’t fix otherwise. On a work PC, ask IT; these settings may be managed by your organisation.

1. Press Win + R, type gpedit.msc and press Enter.
2. Go to Computer Configuration > Administrative Templates > Network > Lanman Workstation, open Enable insecure guest logons, select Enabled and then OK.
3. On Windows 11 24H2, also go to Computer Configuration > Windows Settings > Security Settings > Local Policies > Security Options and set Microsoft network client: Digitally sign communications (always) to Disabled.
4. Restart the PC and open the share again.

Microsoft notes that guest logons can’t use SMB signing or encryption, so both have to be off on the client for a guest connection to work.

Workaround on Home (PowerShell or registry)

Windows Home has no Group Policy Editor. Since 24H2 Home doesn’t require signing or block guest access by default, check the values from the section above first: if either is set, a tweak or an earlier edition upgrade probably changed it. To allow guest access, open Terminal (Admin) and run the commands you need:

Set-SmbClientConfiguration -EnableInsecureGuestLogons $true -Force
Set-SmbClientConfiguration -RequireSecuritySignature $false -Force

These are the client settings documented for the Set-SmbClientConfiguration cmdlet. Microsoft’s troubleshooting article also gives a registry method: under HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\LanmanWorkstation (create the key if it’s missing), add a DWORD value named AllowInsecureGuestAuth set to 1, then restart. If Registry Editor won’t import or save changes, see error accessing the registry.

Some users report that only the signing change fixed it on 24H2, which matches Microsoft’s note that required signing blocks guest access on its own. You don’t need to change any Set-SmbServerConfiguration setting on the PC you’re connecting from, despite what some guides suggest.

How to undo the workaround

Once the NAS has a password or has been replaced, put the defaults back:

• In Group Policy, set Enable insecure guest logons and Microsoft network client: Digitally sign communications (always) back to Not configured.
• Or in PowerShell (Admin), run Set-SmbClientConfiguration -EnableInsecureGuestLogons $false -Force and Set-SmbClientConfiguration -RequireSecuritySignature $true -Force.
• Delete the AllowInsecureGuestAuth registry value if you added it, then restart.

If the share now fails with The network path was not found instead, see error 0x80070035. If the device only speaks the old SMB1 protocol, see “Your system requires SMB2 or higher”.

Related guides

• Error 0x80070035 “The Network Path Was Not Found”: How to Fix It
• How to map a network drive in Windows 10 (and Windows 11)
• “Your system requires SMB2 or higher”: how to fix network share access
• Wi-Fi or VPN stopped connecting after the October 2026 Windows update: the NTLMv1 and MS-CHAPv2 change

Official sources

• Enable insecure guest logons in SMB2 and SMB3 (Microsoft Learn)
• Control SMB signing behavior (Microsoft Learn)
• Can’t access shared folders from File Explorer (Microsoft Learn)