Here’s a complete write-up on the in relation to DirectX , including what it is, why it happens, how to fix it, and how to prevent it. What Is AdvPack.dll? AdvPack.dll is a system DLL file associated with Windows Installer and certain legacy setup utilities. Its full name is Advanced Pack DLL , and it’s part of Microsoft’s operating system components, often used during software installations that involve cabinet (.cab) files or older installation technologies.