How to fix RoundCube’s error: DATABASE ERROR: CONNECTION FAILED!

Mysql server and InnoDB engine must to be running!

Check mysql connection:

cat /usr/local/cpanel/base/3rdparty/roundcube/config/config.inc.php |grep mysql:
$config['db_dsnw'] = 'mysql://roundcube:[email protected](/var/lib/mysql/mysql.sock)/roundcube';
mysql -u roundcube -p
show tables;

All tables should be in place:

+---------------------+
| Tables_in_roundcube |
+---------------------+
| cache               |
| cache_index         |
| cache_messages      |
| cache_shared        |
| cache_thread        |
| contactgroupmembers |
| contactgroups       |
| contacts            |
| cp_schema_version   |
| dictionary          |
| identities          |
| searches            |
| session             |
| system              |
| users               |
+---------------------+
15 rows in set (0.00 sec)

Cpanel keeps roundcube backups here:

/var/cpanel/roundcube

Go ahead and drop broken database

mysqladmin drop roundcube

Rebuild roundcube using the following two commands:

rpm -e --nodeps cpanel-roundcubemail

/usr/local/cpanel/scripts/check_cpanel_rpms --fix

Database roundcube should be recreated automatically.
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