I’ve been using ido with Emacs for some time now and have been running into an error after I create a bunch of files in a directory (like with git format-patch). The problem is ido doesn’t want to list all of the files in the directory, even after I delete them and reboot Emacs.

I found a solution on the EmacsWiki, increase the max directory size for ido.

(setq ido-max-directory-size 100000)

Hope this helps someone who runs into this.