"Plugin '0' is not loaded" - mysql

Question

After upgading MySQL to newer version I have error when I want to connect to server:
ERROR 1524 (HY000): Plugin '0' is not loaded
Any ideas?

Answer 1

This looks like a Bug in MySQL as Bug #60432
Modifying mysql.user table can deny users from logging in . Which states that:
If database manager accidentally (or deliberately) modifies mysql.user
table by adding any column in position lower (or equal) than
"max_user_connections", then after reloading privileges no one is
allowed to log in.
Workaround: Undoing the modification made in user table.

Answer 2

Run following commands
sudo /etc/init.d/mysql stop
sudo mkdir -p /var/run/mysqld; sudo chown mysql /var/run/mysqld
sudo mysqld_safe --skip-grant-tables &
and then press enter
now your password get reset, you can change your password again
This works for me

Answer 3

This is indeed a bug with MySQL and a changed user table structure. Unfortunately, if you don't know what changed, you can't change it back. Also, if you cannot login, you cannot fix anything either.
I fixed this as follows. Please be careful with these instructions as they may not work entirely for your setup and you could lose your data if this goes wrong. Don't blame me if it does!
1. Back-up old data dir
Back-up your old data dir somewhere. This allows you to restore the tables at the end. To find out where your data dir is, you can try to initialise mysql. It will give you an error because the data dir already exists:
mysqld initialize
Output:
mysqld: Can't create directory '/usr/local/mysql/data/' (Errcode: 13 - Permission denied)
Now backup your data dir somewhere:
cp -r /usr/local/mysql/data ~/backup-dir/
2. Re-initialize MySQL
With your data dir safely backed up, remove it and re-initialize mysql. It will give you a new temporary password which you can change later.
rm -rf /usr/local/mysql/data
mysqld initialise
The output will give you a new password for 'root'. If you get permission errors, use sudo (not sure about the drawbacks).
Start the server using mysqld_safe to be sure it works the first time:
mysqld_safe
Optionally, change the root password by logging in to mysql and running alter table:
mysql -u root -p
<enter password>
ALTER USER 'root'#'localhost' IDENTIFIED BY 'New Password';
3.Restore data
Stop the mysql server
mysqld stop
Copy all the backup files to the new data dir (run this for every db you need to restore):
cp -r ~/backup-dir/data/<dbname> /usr/local/mysql/data/
For MyISAM tables, this is enough. If you have InnoDB tables, you also need to copy the InnoDB table space from your backup:
cp ~/backup-dir/data/ibdata* /usr/local/mysql/data/
Then, fix permissions (look at the files already present in /usr/local/mysql/data for the right permissions, mine were 'mysql' for both user and group):
chown -R mysql:mysql /usr/local/mysql/data/*
Start the mysql server
mysqld start
All done! You should be able to login again and your tables should be back containing all data, too.

Answer 4

I found a way to fix this...
change the configuration file --my.cnf (usually in /etc/my.cnf)
add "skip-grant-tables" below [mysqld]
now you can login the mysql! backup your database and re-install mysql
I think this will completely repair the problems.
(Plugin 0 is not loaded, i found i cant backup the database then..so you need to add something in mysql.cnf)

Answer 5

I restarted my MySql server and Apache web server and it worked.