In computing, DLL hell is due to complications that arise when working with dynamic link libraries, (DLLs), in Microsoft Windows operating systems. Although the term is Windows-specific, and the more general term is dependency hell, DLL hell is often used for dependency hell on any platform.

It takes a number of forms, detailed below. This problem often shows up in a Windows alert window that reports: "A Required DLL File, xxxx, was not found" or "The procedure entry point xxxx couldn't be located in xxxx.DLL" when users try to run an application, but can also manifest itself more quietly as applications not working properly.