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Troubleshooting Robocopy Error 1338/87 on Windows Server: Causes and Solutions

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Troubleshooting Robocopy Error 1338/87 on Windows Server

This article addresses a specific issue encountered when utilizing Robocopy to transfer data from CIFS (Common Internet File System) file servers to Windows Server environments. Specifically, it focuses on resolving errors 1338 and 87 that may arise during this process. These errors typically manifest when attempting to copy files along with their associated security attributes. Understanding the root cause and implementing the provided solutions are crucial for ensuring successful and secure data migration and backup operations in Windows Server environments.

Symptoms

When employing Robocopy to duplicate files and their corresponding security settings from a CIFS file server, you might encounter the following errors for certain files. These errors are specifically triggered during the process of copying NTFS security information to the destination. The error messages will appear in the Robocopy log output, providing details about the failure.

yyyy/mm/dd hh:mm:ss ERROR 1338 (0x0000053A) Copying NTFS Security to Destination File <file pathname>
The security descriptor structure is invalid.

yyyy/mm/dd hh:mm:ss ERROR 87 (0x00000057) Copying NTFS Security to Destination File <file pathname>
The parameter is incorrect.

It is important to note that these errors are exclusively observed when copying file security. This is typically initiated by using command-line options such as /SEC or /COPYALL with Robocopy. If file security copying is omitted from the Robocopy command, the file transfer process proceeds without errors, and all files are successfully copied. This distinction highlights that the issue lies specifically within the security descriptor information being processed.

Cause

The underlying cause of these errors is attributed to the CIFS file server providing invalid security information for specific files. This invalid information typically involves a missing or improperly formatted Security Identifier (SID) within the security descriptor. For instance, if the CIFS server returns a NULL SID for either the file’s Owner or the file’s Primary Group, problems will arise when Robocopy attempts to replicate this security information to the destination file system.

Windows operating systems mandate that file security information must include both Owner and Primary Group SIDs. When Robocopy encounters a security descriptor lacking these essential components, the Windows operating system rightly identifies this as an invalid parameter or an invalid security descriptor structure. Consequently, Windows generates either error 87, indicating “The parameter is incorrect,” or error 1338, signifying “The security descriptor structure is invalid.” This behavior is intentional and reflects the design principles of Windows security management.

To illustrate this further, consider the structure of a Security Descriptor. A Security Descriptor contains information about who owns an object (Owner SID), the primary group associated with the object (Primary Group SID), and who is allowed or denied access to the object (Discretionary Access Control List - DACL). The system uses these SIDs to identify security principals (users, groups, computers) within a Windows domain or local system. If the Owner SID or Primary Group SID is missing or invalid, the entire security descriptor becomes structurally flawed from a Windows perspective.

Let’s visualize the concept of Security Descriptor components:

mermaid graph LR SD[Security Descriptor] --> OwnerSID[Owner SID] SD --> GroupSID[Primary Group SID] SD --> DACL[DACL] SD --> SACL[SACL (Optional)] OwnerSID --> SID_Format[Valid SID Format] GroupSID --> SID_Format DACL --> ACEs[Access Control Entries] SACL --> Audit_ACEs[Audit Access Control Entries]

In this diagram, we can see that the Security Descriptor (SD) is composed of several key components. The Owner SID and Primary Group SID are fundamental. If these SIDs are not in a valid format or are missing (NULL), the Windows security subsystem will reject the security descriptor, leading to the Robocopy errors. The DACL and SACL (System Access Control List) control permissions and auditing respectively, but the presence of valid Owner and Group SIDs is a prerequisite for a valid Security Descriptor in Windows.

The error, therefore, does not originate from Robocopy itself, but rather from the invalid security data provided by the source CIFS server. Robocopy is simply reporting the error that Windows generates when it attempts to process this malformed security information. The CIFS server, in this scenario, might be configured incorrectly, or there might be issues with how it manages file security attributes.

Resolution

To resolve errors 1338 and 87 during Robocopy operations from a CIFS server, the focus must be on correcting the security information on the CIFS file server itself. Specifically, it is necessary to identify the files triggering the errors and rectify their security descriptors. The core task is to ensure that all affected files have both a valid Owner SID and a valid Primary Group SID assigned within their security descriptors on the CIFS server.

The specific tools and methods for correcting security information will vary depending on the operating system and configuration of the CIFS file server. However, the general principle remains the same: you need to access the security settings of the problematic files on the CIFS server and ensure that valid SIDs are assigned for both Owner and Primary Group.

Here are general steps and potential tools you might use, depending on the CIFS server environment:

  1. Identify Affected Files: Robocopy error logs pinpoint the <file pathname> that triggers the error. Note these file paths. This is crucial for targeting your remediation efforts.
  2. Access CIFS Server Management Tools: Log in to the administrative interface or server console of your CIFS file server. This could be a Windows Server acting as a file server, a NAS device, or a Linux/Unix-based system running Samba.

  3. Security Management Tools:

    • Windows-based CIFS Server: If the CIFS server is running Windows Server, you can use standard Windows tools:

      • File Explorer (GUI): Navigate to the affected files via File Explorer. Right-click on a file, select “Properties,” then go to the “Security” tab, then “Advanced”. Within the Advanced Security Settings, review the “Owner” and “Group” information. You can change the owner and group if necessary.
      • icacls (Command-line): The icacls command-line utility is powerful for viewing and modifying Access Control Lists and security descriptors. You can use it to examine the security descriptor of a file and set the owner and group. For example, to view the security descriptor: icacls "<file pathname>". To set the owner: icacls "<file pathname>" /setowner "domain\username". To set the group: icacls "<file pathname>" /setgroup "domain\groupname".
      • PowerShell: PowerShell offers cmdlets for managing file system security, such as Get-Acl and Set-Acl. These can be used to inspect and modify security descriptors programmatically.

    • NAS Devices/Samba (Linux/Unix-based): For NAS devices or Samba servers, the tools will depend on the specific vendor or distribution. Common approaches include:

      • Web-based Management Interface: Many NAS devices provide a web interface for file sharing and security management. Explore the settings related to file permissions, ownership, and group assignments.
      • Command-line (SSH): If you have SSH access to the CIFS server (e.g., a Linux-based Samba server), you can use command-line utilities:
        • chown (change owner): chown user:group "<file pathname>". This command changes both the owner and the group.
        • chgrp (change group): chgrp group "<file pathname>". This changes only the group.
        • chmod (change mode - permissions): While primarily for permissions, chmod can sometimes indirectly affect the security context.
        • smbcacls (Samba specific): For fine-grained control over Samba ACLs.

  4. Correct Security Information: Using the appropriate tool, ensure that for each affected file, a valid user or group is set as the Owner and a valid group is set as the Primary Group. If the current owner or group is invalid or missing, change it to a valid domain user/group or a local user/group, as appropriate for your environment. Ensure the SIDs are correctly resolved and not showing up as NULL or unknown values.

  5. Verify Resolution: After correcting the security information on the CIFS server, re-run the Robocopy command that was previously generating errors. Monitor the Robocopy log to confirm that errors 1338 and 87 no longer occur for the remediated files.

Example Scenario using Windows Server as CIFS server:

Let’s say Robocopy reports error 1338 for the file \\CIFSServer\Share\Documents\ProblemFile.docx.

  1. On the Windows Server acting as CIFSServer, open File Explorer and navigate to Share\Documents.
  2. Right-click on ProblemFile.docx and select “Properties”.
  3. Go to the “Security” tab, then click “Advanced”.
  4. In the “Advanced Security Settings for ProblemFile.docx” window, check the “Owner” and “Group” fields at the top.
  5. If the Owner is set to “Account Unknown” or a SID that looks invalid, click “Change” next to “Owner”. Enter a valid user or group (e.g., “Domain Admins” or a specific user account) and click “Check Names” to ensure it resolves correctly. Click “OK”.
  6. Similarly, check the “Group”. If it’s invalid, change it to a valid group.
  7. Click “Apply” and “OK” in the Advanced Security Settings, and then “OK” in the file properties.
  8. Re-run the Robocopy command.

By systematically correcting the security information on the CIFS server, you can eliminate errors 1338 and 87 and ensure successful Robocopy operations, including the accurate transfer of file security attributes.

More Information

The occurrence of errors 1338 and 87 during Robocopy operations when copying security from CIFS servers underscores the fundamental requirement for valid security descriptors in Windows. As emphasized, Windows expects each file’s security information to contain both an Owner SID and a Primary Group SID. This is not merely a recommendation but a core design principle of the Windows security model.

Security Descriptors (SDs) and Access Control Lists (ACLs) are central to how Windows manages permissions and security. Understanding these concepts is crucial for troubleshooting issues like the Robocopy errors discussed.

  • Security Descriptor (SD): A binary data structure that contains security information for a securable object (like a file, folder, registry key, process, etc.). It includes:

    • Owner SID: Identifies the security principal (user or group) who owns the object. The owner typically has control over who can access the object.
    • Primary Group SID: Used primarily by the POSIX subsystem. In a typical Windows environment, this might be less critical than the Owner SID in terms of access control, but it is still a required part of a valid security descriptor.
    • DACL (Discretionary Access Control List): Defines who is allowed or denied specific types of access to the object. It contains Access Control Entries (ACEs) that specify permissions for individual users or groups.
    • SACL (System Access Control List): Controls auditing. It defines which access attempts (successful or failed) should be logged in the security event log.

  • Security Identifier (SID): A unique, variable-length identifier used to represent security principals (users, groups, computers, services). SIDs are fundamental to Windows security. When you grant permissions to a user or group, you are actually associating their SID with an object’s DACL.

The errors 1338 and 87 arise because when the CIFS server provides a security descriptor with a missing or invalid Owner or Primary Group SID, Windows’ security subsystem flags this as an invalid security descriptor. This is a security mechanism to prevent the propagation of potentially flawed or incomplete security information.

Why might a CIFS server provide invalid security information?

Several reasons could lead to a CIFS server presenting invalid security descriptors:

  • Legacy Systems: Older CIFS servers or NAS devices might not fully adhere to modern Windows security descriptor requirements, especially when dealing with older file systems or permission models.
  • Interoperability Issues: Differences in how security attributes are handled between different operating systems (e.g., Windows vs. Unix-like systems underlying some NAS devices) can sometimes lead to inconsistencies or data loss during translation.
  • File System Corruption: In rare cases, file system corruption on the CIFS server could lead to damaged security descriptors.
  • Incorrect Security Configuration: Misconfiguration of permissions or security settings on the CIFS server itself could result in invalid security descriptors being generated.

In summary: Errors 1338 and 87 during Robocopy security copying from CIFS servers are indicators of invalid security descriptors originating from the source. The resolution lies in correcting the security information on the CIFS server to ensure that all files have valid Owner and Primary Group SIDs. Understanding the role of Security Descriptors and SIDs in Windows is key to effectively diagnosing and resolving these types of security-related file transfer issues.

If you continue to experience issues after implementing the resolutions described, further investigation into the CIFS server’s configuration and file system health might be necessary. Consult the documentation for your specific CIFS server platform for more detailed guidance on security management and troubleshooting.

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