To fix the ui.ff error in Call of Duty: Modern Warfare 2 , you must , as downloading individual fastfiles ( .ff ) from unofficial third-party websites can expose your PC to malware and often fails to resolve the underlying game corruption.
The ui.ff file is only 2–5 MB in size. It is not worth visiting sketchy ad-filled download sites that disguise a "Download Now" button as a fake play button. Every legitimate problem involving this file can be solved by: call of duty modern warfare 2 ui.ff download