ERROR_NOT_REGISTRY_FILE - 1017 (0x3F9)
The system has attempted to load or restore a file into the registry, but the specified file is not in a registry file format.
Updated: Feb 21, 2026
Technical Meaning
The error code ERROR_NOT_REGISTRY_FILE with the numeric value of 1017 and hexadecimal representation of 0x3F9 indicates that an attempt was made to load or restore a file into the Windows registry, but the specified file does not conform to the expected format for registry files.
Error Details
This error typically occurs when a utility or application attempts to process a file as if it were a Windows registry file (.reg), but the file contents do not match the required structure. The registry files are designed with specific formats and structures, which include key-value pairs, sections, and other metadata that must be present for successful processing.
Usage Context
This error can arise in various scenarios where registry operations are performed, such as during system restoration, application installation, or manual editing of the registry. It is particularly relevant when dealing with .reg files, which are text-based files used to export and import portions of the Windows Registry.
Developer Interpretation
Developers should interpret this error code as an indication that the file being processed does not meet the necessary format requirements for a valid registry file. This could be due to incorrect content, missing sections, or other structural issues within the file. Developers are advised to ensure that any files intended for registry operations adhere strictly to the expected format.
Related Errors
ERROR_FILE_NOT_FOUND(2)ERROR_INVALID_PARAMETER(87)ERROR_BAD_FORMAT(19)
FAQ
Q: What does ERROR_NOT_REGISTRY_FILE mean?
A: This error indicates that a file intended for registry operations is not in the correct format.
Q: How can I resolve this issue?
A: Ensure that any files used for registry operations are correctly formatted and contain valid registry data. Use tools like regedit to validate or repair the file if necessary.
Summary
The ERROR_NOT_REGISTRY_FILE error code is a specific technical indicator that a file intended for registry operations does not conform to the required format. Developers should ensure their files meet these requirements to avoid encountering this error during system operations.