A condition in which data on a digital medium has been corrupted. The error can be as little as one bit.

In DOS, the message "Data error on drive x" means that an area of the disk is unreadable. Press R to retry. Most likely, you'll have to press A to stop (abort). If the data or program is critical and there's no backup, use a utility program to try to reconstruct the damaged area. See DOS Recover.