When attempting to load a LISP application or a MNU/CUI menu, AutoCAD displays the error:
; error: bad character read (octal): N
The reason is in an improperly formatted LSP (or MNL) file. A LISP application must be in a text format, without any control (binary) characters.
Such special characters may get into your file either through a technical error (disk or communication error, virus), or simply by editing the file in Word or WordPad (they both add control characters), not in the classic Notepad or other plain text editor. Or this is is simply not a LISP file but e.g. a renamed EXE file.