Knowledge

ERROR_EFS_SERVER_NOT_TRUSTED - 6011 (0x177B)

The server is not trusted for remote encryption operation.

Updated: Feb 21, 2026

Technical Background

The ERROR_EFS_SERVER_NOT_TRusted error code, with the numeric value 6011 and hexadecimal representation 0x177B, indicates that a remote server is not trusted for performing encryption operations within the Encrypting File System (EFS) framework. This error typically arises in scenarios where EFS is being used to encrypt files on a network share or across multiple servers.

Error Details

The ERROR_EFS_SERVER_NOT_TRusted error signifies that the server hosting the encrypted file(s) has not been properly configured or authenticated for use with EFS. This can occur due to various reasons, such as misconfiguration of the server's security settings, lack of proper trust relationships between the client and the server, or issues related to the EFS certificate infrastructure.

Common Causes

  • Misconfigured Security Settings: The server may not have the necessary permissions or certificates required for EFS operations. Ensure that the server has been properly enrolled in the EFS certificate authority (CA) and that its certificate is correctly installed and trusted by the client machine.
  • Incorrect Trust Relationships: There might be issues with trust relationships between the client and the server. Verify that both machines are part of the same domain or have established a secure trust relationship through other means, such as Kerberos authentication.
  • EFS Certificate Issues: The EFS certificate on the server may be invalid, expired, or revoked. Check the certificate status and ensure it is valid and properly issued by a trusted CA.

Real-World Context

This error can occur in environments where files are stored remotely and need to be encrypted for security purposes. It is particularly relevant in scenarios involving networked file servers, cloud storage solutions, or any environment where EFS is used across multiple machines.

Is This Error Critical?

The ERROR_EFS_SERVER_NOT_TRusted error can have significant implications for data security and integrity. If this error occurs, it may prevent users from accessing encrypted files stored on the server, leading to potential data loss or unavailability issues. Therefore, addressing this error is critical to maintaining a secure file system environment.

How to Diagnose

To diagnose the ERROR_EFS_SERVER_NOT_TRusted error, follow these steps:

  1. Review Security Settings: Ensure that the server has been properly configured for EFS and that it holds valid certificates issued by a trusted CA.
  2. Verify Trust Relationships: Check if there are any issues with trust relationships between the client and the server. This can be done through domain membership or Kerberos configuration checks.
  3. Check Certificate Status: Validate the status of the EFS certificate on the server to ensure it is valid and not expired or revoked.

How to Resolve

To resolve the ERROR_EFS_SERVER_NOT_TRusted error, take the following actions:

  1. Correct Security Settings: Ensure that the server has been properly enrolled in the EFS CA and that its certificate is correctly installed and trusted by the client machine.
  2. Establish Trust Relationships: Verify and establish proper trust relationships between the client and the server if they are not already established.
  3. Restore Certificates: If the EFS certificate on the server is invalid or expired, obtain a new valid certificate from a trusted CA and install it on the server.

Developer Notes

Developers should ensure that their applications handle this error gracefully by providing appropriate feedback to users and logging detailed error information for troubleshooting purposes. Additionally, they should implement robust security measures to prevent such errors from occurring in the first place.

Related Errors

  • ERROR_EFS_NOT_ALLOWED (6012): Indicates that EFS is not allowed on the file system or drive.
  • ERROR_EFS_NO_RECOVERY_KEY (6013): Indicates that no recovery key is available for the encrypted files.
  • ERROR_EFS_NO_USER_KEYS (6014): Indicates that there are no user keys associated with the encrypted files.

FAQ

Q: What does the ERROR_EFS_SERVER_NOT_TRusted error mean?

A: The server hosting the encrypted file(s) is not trusted for performing encryption operations within the EFS framework. This can occur due to misconfigured security settings, incorrect trust relationships, or issues with EFS certificates.

Q: How do I resolve this error?

A: Ensure that the server has been properly configured for EFS and that it holds valid certificates issued by a trusted CA. Verify and establish proper trust relationships between the client and the server if necessary. If the certificate is invalid or expired, obtain a new valid certificate from a trusted CA and install it on the server.

Q: Is this error critical?

A: Yes, addressing this error is critical to maintaining data security and integrity in environments where EFS is used across multiple machines.

Summary

The ERROR_EFS_SERVER_NOT_TRusted error code indicates that a remote server is not trusted for performing encryption operations within the EFS framework. This can occur due to misconfigured security settings, incorrect trust relationships, or issues with EFS certificates. Addressing this error involves ensuring proper configuration and establishing secure trust relationships between the client and the server.