Windows App Compatibility Fix Registry Locations

This article provides the exact Windows Registry locations where system-wide application compatibility fix database entries and compatibility layer settings are stored. It details the specific paths within HKEY_LOCAL_MACHINE used by the Windows Application Compatibility infrastructure (AppCompat) to register shim databases and maintain executable-specific compatibility fixes across the entire operating system.

Installed Application Compatibility Databases (InstalledSDB)

System-wide registered compatibility databases (SDB files) are tracked in the registry under the InstalledSDB key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\InstalledSDB

On 64-bit systems managing 32-bit specific database entries, the corresponding WOW64 path is:

HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\InstalledSDB

Each installed database is stored as a subkey named with the database’s unique GUID (for example, {GUID}). Inside each GUID key, you will find: * DatabasePath: A string value pointing to the physical .sdb file (typically in C:\Windows\AppPatch\Custom\ or C:\Windows\AppPatch\Custom\Custom64\). * DatabaseType: A DWORD value indicating the database type (e.g., system or custom). * DatabaseDescription: The friendly name assigned to the compatibility fix database.

System-Wide Executable Compatibility Layers (Layers)

If application compatibility settings (such as Windows version spoofing, DPI scaling overrides, or administrative privilege enforcement) are applied system-wide to specific applications, they are stored in the Layers key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Layers

For 32-bit applications on 64-bit Windows:

HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Layers

Within the Layers key: * Value Name: The full file path to the executable (e.g., C:\Program Files\Example\App.exe). * Value Type: REG_SZ (String Value). * Value Data: Space-separated compatibility flags applied to that executable (e.g., WINXPSP3 RUNASADMIN HIGHDPIAWARE).

Compatibility Mitigation Flags (Compatibility Assistant)

General compatibility flags, telemetry data, and block lists managed by the Program Compatibility Assistant (PCA) reside under:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Compatibility Assistant\Store

This key contains binary values tracking the execution history and compatibility status of programs evaluated by Windows.