IBM Support

Windows 10 cannot access \\NetServer_Name using GUEST Support when SMB signing is required



Windows® 10 PCs fail to map a NetServer network drive when NetServer is using SMB2.  The following error is received:
 Network Error                                                           
 Windows® cannot access \\NetServer_Name                                        
 Check the spelling of the name. Otherwise, there might be a problem with your network. To try to identify and resolve network problems, click Diagnosis                                     
 Error code 0x80004005                                                 
 Unspecified Error    


TRCCNN, collected on the IBM i, shows the following sequence:
R - SYN                                                                   
S - SYN ACK                                                               
R - NEGOTIATE                                                             
S - SMB2_NEGOTIATE                                                        
R - SMB2_SESSION_SETUP                                                    
S - SMB2_SESSION_SETUP 'accept_incomplete'                               
R - SMB2_SESSION_SETUP                                                    
S - SMB2_SESSION SETUP SMB2_SESSION_FLAG_IS_GUEST                         


This error is caused by the client PC attempting to make a guest connection to the server when the client is configured to require SMB signing.  There is no secret key available to decrypt the client session key for guest connections, so the server cannot sign the session setup response.  Windows® appears to have security enhancements in place on the client that are preventing the unsecured connection to the server.
Microsoft® support document 'Guest access in SMB2 disabled by default in Windows' describes the issue.  At the time of this writing, the document is found here:

Resolving The Problem

Follow recommendations provided by Microsoft®.

Document Location


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Document Information

Modified date:
18 December 2019