As well as information about side by side assemblies (ie: library versions), a Windows manifest file has various settings and a declaration of compatible versio

As well as information about side by side assemblies (ie: library versions), a Windows manifest file has various settings and a declaration of compatible versions of Windows that affect Windows' handling of the app, such as whether it can handle paths over MAX_PATH, if it is hi-dpi aware, or if it knows about themed controls. https://learn.microsoft.com/en-us/windows/win32/sbscs/application-manifests https://learn.microsoft.com/en-us/windows/win32/sbscs/applic... If an EXE doesn't have a manifest file, Windows assumes that it's ancient, so it falls back to conservative defaults like ye olde USER controls to try and avoid breaking it.