引用 I just encountered a similar problem on one of my production servers this morning. (I'm still investigating the cause.) After doing a quick bit of Google-searching, this solved my problem:
mysqladmin -u <username> -p flush-tables
By the way: All directories in /var/lib/mysql should have 700 permissions (owned my the mysql user) and everything within those directories should be 660 (owned by the mysql user and mysql group).