| Previous | Next |
| ERROR_MACHINE_LOCKED | ERROR_CALLBACK_SUPPLIED_INVALID_DATA |
ERROR_SMB_GUEST_LOGON_BLOCKED
This is a security-policy failure, not a bad share name. Microsoft documents that modern Windows SMB2/SMB3 clients block guest access or fallback to Guest by default on many current editions and recommends upgrading devices or software that require unauthenticated guest authentication. Recent SMB signing requirements can create additional incompatibility because guest logons do not support the normal signing/encryption security model.
Confirm what the server actually offered. A Samba share configured with guest access can intentionally map clients to a guest account, while an authenticated share should establish a real user security context. Fixing the server to support authenticated SMB is safer than globally weakening the Windows client policy merely to make the error disappear.
Verify the authentication mode
- Inspect SMB session setup and determine whether the server accepted or mapped the client as Guest.
- Check the share/server configuration for guest-only or guest-fallback behavior.
- Prefer configuring authenticated access on the server or upgrading the device/software.
- If insecure guest logons are deliberately enabled for a controlled compatibility case, document the signing/encryption tradeoff and scope the exception.
Microsoft SMB guest logon policy · Samba standalone server and guest shares · Samba smb.conf manual
Looking for a different code? Search another status or error code.