WP Toolkit backup fails: mysqldump: Character set 'DB_CHARSET' is not a compiled character set

Symptoms

WP Toolkit backups fail with an error like the following.

mysqldump: Character set 'utf8bm4' is not a compiled character set and is not specified in the '/usr/share/mysql-8.0/charsets/Index.xml' file

Description

This error can occur if the DB_CHARSET is defined incorrectly in the wp-config.php file for the site. In the example above, the DB_CHARSET is defined as utf8bm4 instead of utf8mb4.

The command below can be used to check the current DB_CHARSET setting for the site, replacing "/home/ACCT/public_html/wp-config.php" with the actual path to the wp-config.php file for the site.

grep DB_CHARSET /home/ACCT/public_html/wp-config.php
define( 'DB_CHARSET', 'utf8bm4' );

Workaround

The wp-config.php file for the site will need to be manually corrected.

How to edit a file on command-line