Class not registered

Class Not Registered on Windows often involves system components that do not exist on Linux or macOS: the Windows Registry, User Account Control (UAC), and the Windows Service Control Manager. Understanding which component is involved determines the correct fix. Registry-related causes: application settings stored in HKEY_CURRENT_USER are not available when the application runs as a different user (e.g., a Windows Service running as SYSTEM). Use HKEY_LOCAL_MACHINE for settings that must be accessible across all users. UAC-related causes: running an application without elevation when it requires Administrator privileges fails silently or with an access denied error similar to Class Not Registered. Right-click → "Run as administrator" tests this, but the permanent fix is to adjust the application's manifest to request the correct privilege level. Windows Service differences: services run without a desktop session, cannot display UI elements, and use the service account's profile rather than any logged-in user's profile. Use Event Viewer (eventvwr.msc) → Windows Logs → Application for service errors that are not shown in the console.