Knowledge

ERROR_REPARSE_TAG_INVALID - 4393 (0x1129)

The tag present in the reparse point buffer is invalid.

Updated: Feb 21, 2026

Technical Background

The ERROR_REPARSE_TAG_INVALID error code is a specific Windows API error that indicates an issue with the reparse point buffer. Reparse points are used by the file system to provide special handling for certain files or directories, such as symbolic links, mount points, and junctions.

Error Details

The ERROR_REPARSE_TAG_INVALID error code (4393, 0x1129) is returned when a reparse point buffer contains an invalid tag. This can occur during operations that involve the manipulation or processing of reparse points, such as file enumeration, directory traversal, or symbolic link handling.

Common Causes

  • Invalid Parameter Values: The operation was performed with an invalid reparse point tag.
  • Incorrect Object Type: The object being processed is not a valid reparse point.
  • Corrupted Data: The reparse point buffer may be corrupted, leading to the presence of an invalid tag.

Real-World Context

This error can occur in various scenarios where reparse points are involved. For example, when attempting to traverse a directory that contains a symbolic link or mount point, if the reparse point data is malformed or incorrect, this error will be generated.

Is This Error Critical?

The criticality of this error depends on the context in which it occurs. In most cases, it indicates an issue with file system metadata and does not necessarily indicate a severe system failure. However, if this error persists, it may lead to issues such as incorrect file handling or directory traversal.

How to Diagnose

  1. Review Operation Context: Ensure that the operation is being performed in the correct context (e.g., within a valid directory).
  2. Validate Parameters: Verify that all parameters passed to the API are correct and valid.
  3. Confirm Object Types: Check if the object being processed is indeed a reparse point.

How to Resolve

  1. Correct Parameter Usage: Ensure that all parameters, including the reparse point tag, are correctly specified.
  2. Adjust Operation Context: If the operation context is incorrect, adjust it to ensure proper handling of reparse points.
  3. Restore Data: If data corruption is suspected, restore or repair the affected file system metadata.

Developer Notes

  • When working with reparse points, always validate the tag and ensure that all operations are performed within a valid context.
  • Be cautious when modifying or creating reparse points to avoid introducing invalid tags.

Related Errors

  • ERROR_REPARSE_POINT: Indicates an issue with a reparse point itself.
  • ERROR_INVALID_PARAMETER: A more general error indicating invalid parameters, which may include incorrect reparse point tags.

FAQ

Q: What does the ERROR_REPARSE_TAG_INVALID error mean?

A: It indicates that an invalid tag was found in a reparse point buffer during file system operations.

Q: How can I prevent this error from occurring?

A: Ensure all parameters are correct and valid, especially when dealing with reparse points. Validate the object types before processing them.

Q: Can this error be caused by hardware issues?

A: No, this is a software error related to file system metadata and does not indicate a hardware issue.

Summary

The ERROR_REPARSE_TAG_INVALID error code (4393, 0x1129) indicates an invalid tag in a reparse point buffer. This can occur due to incorrect parameters or corrupted data. By validating parameters and ensuring correct operation context, developers can prevent this issue.