ERROR_USER_MAPPED_FILE - 1224 (0x4C8)
The requested operation cannot be performed on a file with a user-mapped section open.
Updated: Feb 21, 2026
Technical Meaning
The ERROR_USER_MAPPED_FILE error code indicates that an operation attempted on a file could not be completed because the file has been opened for user-mapping. User-mapped files are typically used in scenarios where direct memory access is required, such as when loading shared libraries or performing certain types of inter-process communication.
Error Details
This error occurs when attempting to perform an operation that conflicts with the current state of a file object. Specifically, it arises when trying to modify a file while it has been mapped into user space by another process or thread. This can happen in situations where multiple processes are accessing the same file simultaneously.
Usage Context
The ERROR_USER_MAPPED_FILE error is commonly encountered in scenarios involving shared memory or inter-process communication (IPC) mechanisms that rely on mapping files directly into memory spaces. It may also appear when attempting to perform operations such as renaming, deleting, or modifying a file while it remains mapped by another process.
Developer Interpretation
Developers should be aware of the implications of user-mapped files and ensure that their code handles these scenarios appropriately. When encountering this error, developers should review the operation context and verify that all processes involved have properly unmapped the file before attempting further operations.
Related Errors
FAQ
Q: What does the ERROR_USER_MAPPED_FILE error mean?
A: It indicates that an operation could not be performed on a file because it has been opened for user-mapping.
Q: How can I resolve this issue?
A: Ensure that all processes have properly unmapped the file before attempting further operations. Review the operation context and verify parameter usage.
Summary
The ERROR_USER_MAPPED_FILE error code is a specific technical indicator used by Windows to prevent certain operations on files that are currently mapped into user space. Developers should be mindful of this scenario when designing applications that interact with shared memory or perform file operations in parallel.