Fix “An Extended Error Has Occurred” When Accessing Shared Folders in Windows 11 24H2

After upgrading to Windows 11 version 24H2, some users report that they can no longer open certain shared folders.
The error usually says:

“An extended error has occurred.”

Interestingly, the problem often appears only with one specific Windows 10 computer, while access to other PCs still works fine.
This behavior is related to recent SMB (Server Message Block) security changes in Windows 11.

Let’s go step-by-step through the causes and fixes

💡 To make it easier, I’ve already created simple .reg files for each fix.
Just download the file below and run it, and the registry setting will be applied automatically — no manual editing required.

1️⃣ Enable SMB 1.0/CIFS File Sharing Support

Cause:
Windows 11 disables the old SMB 1.0 protocol for security reasons.
Some legacy Windows 10 PCs or NAS devices still rely on SMB 1.

Fix:
Manually turn it on or use the registry file below.

Manual Steps

1. Open Control Panel → Programs → Turn Windows features on or off

2. Check “SMB 1.0/CIFS File Sharing Support.”

3. Click OK and restart.

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2️⃣ Disable Mandatory SMB Digital Signature

Cause:
Starting with Windows 11 24H2, Microsoft now requires digital signing for all SMB connections.
Older systems that don’t support signing will be rejected.

Fix:
Disable the “always sign” requirement through Local Group Policy or the registry.

 Manual Steps

1. Run gpedit.msc

2. Go to Computer Configuration → Windows Settings → Security Settings → Local Policies → Security Options

3. Find “Microsoft network client: Digitally sign communications (always)”

4. Set to Disabled

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3️⃣ Allow Unsecured Guest Logons

Cause:
The 24H2 update blocks anonymous (guest) logons by default.
If the shared folder uses guest access, Windows refuses the connection.

Fix:
Re-enable guest logons.

Manual Steps

1. Run gpedit.msc

2. Navigate to Computer Configuration → Administrative Templates → Network → Lanman Workstation

3. Set “Enable insecure guest logons” to Enabled

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4️⃣ Enable Network Discovery Service

Cause:
If the Function Discovery Resource Publication service is stopped,
other computers may not find your shared folders.

Fix:
Turn the service back on.

Manual Steps

1. Run services.msc

2. Find Function Discovery Resource Publication

3. Right-click → Properties → Startup type: Automatic

4. Click Start

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Conclusion

Each of these settings addresses a specific SMB-related change in Windows 11 24H2.
Apply them one by one — or download the ready-made registry scripts below for faster repair.

💡 Always back up your registry before applying any .reg file.
(In Regedit → File → Export → Save backup.)