Problem while backup database! (1 reply)

Database backup failed : mysqldump failed :

mysqldump: Couldn't execute 'SHOW FUNCTION STATUS WHERE Db = 'stats'': Column count of mysql.proc is wrong. Expected 20, found 16. Created with MySQL 50142, now running 50146. Please use mysql_upgrade to fix this error. (1558)

I got this error
and when I write "mysql" in my SSH box I got this

[root@cs ~]# mysql
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)


what problem could be? Thanks