RegUnLoadKeyA function (winreg.h)

Unloads the specified registry key and its subkeys from the registry.

Applications that back up or restore system state including system files and registry hives should use the Volume Shadow Copy Service instead of the registry functions.


  [in]           HKEY   hKey,
  [in, optional] LPCSTR lpSubKey


[in] hKey

A handle to the registry key to be unloaded. This parameter can be a handle returned by a call to RegConnectRegistry function or one of the following predefined handles:


[in, optional] lpSubKey

The name of the subkey to be unloaded. The key referred to by the lpSubKey parameter must have been created by using the RegLoadKey function.

Key names are not case sensitive.

For more information, see Registry Element Size Limits.

Return value

If the function succeeds, the return value is ERROR_SUCCESS.

If the function fails, the return value is a nonzero error code defined in Winerror.h. You can use the FormatMessage function with the FORMAT_MESSAGE_FROM_SYSTEM flag to get a generic description of the error.


This function removes a hive from the registry but does not modify the file containing the registry information. A hive is a discrete body of keys, subkeys, and values that is rooted at the top of the registry hierarchy.

The calling process must have the SE_RESTORE_NAME and SE_BACKUP_NAME privileges on the computer in which the registry resides. For more information, see Running with Special Privileges.


The winreg.h header defines RegUnLoadKey as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.


Requirement Value
Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Target Platform Windows
Header winreg.h (include Windows.h)
Library Advapi32.lib
DLL Advapi32.dll

See also





Registry Functions

Registry Overview