MySQL dump throws an error like the following while dumping a database.
Can't find file: 'TABLENAME' (errno: 2)
This can occur if a table is missing its data files and only has the structure file. This can be verified with the following command, where DATABASENAME is the database you are dumping, and TABLENAME is the table in the error.
If only an FRM file exists, there are missing files.
The database will need to be restored from backups.