I decided to start this article, which I intend to keep adding to over time, because I was unable to find a solution to my problem through searches. I hope this information helps people.
Problem: codepage cp437 not found
Solution: I encountered this error when I was trying to slim down my Debian Stretch installation. Through trial-and-error, I was trying to figure out what all is unnecessary in order to run a small headless/no GUI system. I had deleted directories in the fs/ directory, which corresponded to file system types I didn’t expect to encounter on that system. The important directory was “nls/”. This directory contains code pages with characters that the terminal needs in order to display certain text correctly. I personally don’t care how fancy or bad the fonts look on a console, especially if I plan to run it headless.