You can't access this shared folder because your organization's security policies block unauthenticated guest access

Windows refused to open a share because the other side asked for a guest (no user name, no password) sign in. This is the Windows 11 24H2 error above.

What it means

Windows blocks guest logons to remote shares by default. Microsoft’s documentation says:

• Since Windows 10 version 1709 and Windows Server 2019, SMB2 and SMB3 clients do not allow guest access to a remote server by default, or a fall back to the Guest account after wrong credentials.
• In Windows 11 Pro Insider Preview build 25267 and later builds, guest credentials cannot be used to connect to a remote share by default.
• In Windows 11 version 24H2, SMB signing is required by default on the Pro, Enterprise and Education editions (not on Home). That causes problems with guest authentication, because signing does not work with guest.

The message says “your organization”, but on a PC you own it is usually just the Windows default. A managed work PC can also have a policy that sets it.

Why it happens

You are connecting to something that offers a share without accounts. Typical cases are a NAS, a router with a USB drive, or another PC that shares a folder to “Everyone” with no password. Microsoft’s own advice is to upgrade or replace software or devices that only support guest authentication.

How Devpit fixes or avoids it

Devpit does not change these Windows policies.

Share Files avoids guest access on purpose. When you share a folder, Devpit creates a temporary login just for that share, shows its user name and password, and removes it when sharing stops. The receiving PC signs in with a real account, so Windows has no reason to block it. If Windows still blocks a sign-in (error 1272), Devpit says “Windows blocked the sign-in” and tells you not to turn off SMB signing.

The manual fix

Best to least safe:

1. Use a real account (recommended). On the device that shares, create a user with a password, and sign in with it. If Windows says the user name or password is wrong, see system error 1326.

2. Allow insecure guest logons on your PC. Only if you must. Microsoft warns that this can expose you to fake servers and other attacks. In PowerShell as administrator:

Set-SmbClientConfiguration -EnableInsecureGuestLogons $true -Force

Or with the Local Group Policy Editor: run gpedit.msc, then go to Computer Configuration, Administrative Templates, Network, Lanman Workstation, open Enable insecure guest logons, select Enabled and click OK.

Or with the registry: under HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\LanmanWorkstation (create the key if needed) add a DWORD (32-bit) value named AllowInsecureGuestAuth and set it to 1.

Microsoft also says that SMB signing and SMB encryption policies must be disabled in Group Policy to use guest logons, and that this can leave you open to credential theft and relay attacks. That is a good reason to prefer option 1.

3. Turn it off again when you are done. Set the same policy to Disabled, or set EnableInsecureGuestLogons back to $false.

Sources

• Microsoft: Can’t access shared folders from File Explorer (this error and the registry and Group Policy fixes)
• Microsoft: How to enable insecure guest logons in SMB2 and SMB3
• Microsoft: Control SMB signing behavior (which 24H2 editions require signing)
• Microsoft Q&A: the error message text