I got my Famicom replaced recently and began playing my FDS. I have spent the past few hours gunning through Castlevania, which ended on a rather disappointing note. To my dismay, I finally beat Dracula only to receive an Err. 27 message when flipping the disk to view the credits. After a few minutes of playing with the disk, I decided to try beating him again and still I got an Err. 27. The only other time I received an Err. 27 before this was periodically when starting up the game file. However, it worked when I inserted the disk again. Does anyone know why this only happens when loading the credits and not anywhere else? Is it the disk or the system? Please help, I really want to see the ending!
ERR 27 is CRC error. There is probably some dirt on the surface or(bad scenario) damage. Try to clean surface very gently with cotton stick and IPA.