Users usually search for a download of "En-core-pre-gfx.ff" because of:

If you are using a different language (e.g., French or Spanish), the game might be looking for fr-core-pre-gfx.ff instead. Switching the language back and forth can sometimes trigger the correct download. 4. Reinstall the "Core" or "Campaign" Pack

In the Infinity Engine (used for Call of Duty ), (FastFiles) are compressed archives that contain everything the game needs to load a specific level or menu quickly, including textures, sounds, and geometry. "en" : Stands for English (the language localization).