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Fix SMB Shares After the Windows 11 24H2 Update

After the Windows 11 24H2 update, some computers can no longer open shared folders on a NAS, an older server or another computer. This is because 24H2 tightened two security settings for file sharing (SMB). Here's how to check them and get your shares working again.

What changed in 24H2

  • SMB signing is required Windows now insists that file-sharing traffic is signed, to stop it being tampered with. Older NAS boxes and servers that don't support signing are refused.
  • Guest access is blocked Shares that let anyone connect without a username and password no longer open.

You'll usually see an error such as "You can't access this shared folder because your organization's security policies block unauthenticated guest access", or the share simply won't connect.

The best fix: update the share

Where you can, fix the device that holds the share rather than lowering security on every computer:

  • Add a username and password Set up a user account for the share on the NAS or server, and connect with it instead of as a guest.
  • Turn on SMB signing Most NAS boxes have this in their file-sharing settings, often after a firmware update.

Check the current settings

On the Start menu, type powershell, then under Windows PowerShell click Run as administrator and accept the prompt.

Get-SmbClientConfiguration | Select-Object RequireSecuritySignature, EnableInsecureGuestLogons
Shows whether signing is required and whether guest access is allowed.

Turn the settings back

If the share can't be updated, you can turn these settings back to how they were before 24H2. Run each command in an administrator PowerShell window, and press Y then Enter to confirm.

Set-SmbClientConfiguration -RequireSecuritySignature $false
Stops requiring SMB signing, so devices that don't support it can connect.
Set-SmbClientConfiguration -EnableInsecureGuestLogons $true
Allows guest access to shares that don't use a username and password.

This makes file sharing less secure. Only use it on a home or office network you trust, and change only the setting you need.

Undo the change

Set-SmbClientConfiguration -RequireSecuritySignature $true
Requires SMB signing again.
Set-SmbClientConfiguration -EnableInsecureGuestLogons $false
Blocks guest access again.