Windows error 1404 (ERROR_INVALID_HOOK

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: the hook handle does not identify an installed Windows hook.

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ERROR_INVALID_ACCEL_HANDLE	ERROR_INVALID_DWP_HANDLE

ERROR_INVALID_HOOK_HANDLE

The HHOOK is invalid

An HHOOK is returned by SetWindowsHookEx for one installed hook instance. It is not a hook type number, thread identifier, callback address, or module handle.

Hook cleanup is asynchronous enough to expose stale-handle bugs in shared code. A component may unhook during shutdown while another path tries to remove or otherwise reference the same hook. Double-unhook logic and storing the result of a failed SetWindowsHookEx call are also high-value suspects.

What to check

Check that SetWindowsHookEx returned a non-NULL handle and preserve its original error if it did not.
Serialize hook installation and removal so one owner performs cleanup.
Clear the stored handle only after deciding how concurrent callers observe removal.
Keep idHook, dwThreadId, hmod, and the returned HHOOK in separate typed fields.

ERROR_HOOK_NOT_INSTALLED describes installation state; this code means the handle value supplied as an HHOOK is invalid.

References

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