MySQL升級後：ERROR 2013 (HY000): Lost connection to MySQL server during query

升級MySQL後（5.5 -> 5.6.10），MySQL中執行grant命令，或者shell中執行mysqladmin修改密碼，出現類似下面的錯誤：

ERROR 2013 (HY000): Lost connection to MySQL server during query

解決方案：原來是忘了執行mysql_upgrade，執行sudo mysql_upgrade，修復權限表。