See https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/wdm/nf-wdm-rtlqueryregistryvalues The RTL_REGISTRY_OPTIONAL applies to the first parameter of the RtlQueryRegistryValues() function, not to the Flags member of the table entries. However, a RTL_QUERY_REGISTRY_REQUIRED flag exists to mark values whose existence is NOT optional. Problematic usage was introduced in the following modules: drivers/input/i8042prt: Commit e7e959fb0 (r30000) drivers/input/kbdclass: Commit 5a77f871d (r18911) drivers/input/mouclass: Commit aeeab7d1f (r18906) drivers/input/sermouse: Commit 3f348259c (r19100) rosapps/drivers/green : Commit c8a90f769 (r21165)