1. Init phpunit and run the following testcase, confirming that it is passing: vendor/bin/phpunit --filter core_blocklib_testcase 2. In a installed site, using you DB manager or CLI confirm , that the index is created. Eg for mysql: mysql> show create table mdl_user_preferences\G *************************** 1 . row *************************** Table: mdl_user_preferences Create Table: CREATE TABLE `mdl_user_preferences` ( `id` bigint( 10 ) NOT NULL AUTO_INCREMENT, `userid` bigint( 10 ) NOT NULL DEFAULT '0' , `name` varchar( 255 ) NOT NULL DEFAULT '' , `value` varchar( 1333 ) NOT NULL DEFAULT '' , PRIMARY KEY (`id`), UNIQUE KEY `mdl_userpref_usenam_uix` (`userid`,`name`), KEY `mdl_userpref_nam_ix` (`name`) ) ENGINE=InnoDB AUTO_INCREMENT= 4 DEFAULT CHARSET=utf8mb4 ROW_FORMAT=COMPRESSED COMMENT= 'Allows modules to store arbitrary user preferences' 1 row in set ( 0.00 sec) 3. If your DB was upgraded and the index was created via upgrade script then run the following command to confirm , that current DB state matches the install.xml files: root @f5f1a3f62cb1 :/siteroot# php admin/cli/check_database_schema.php Database structure is ok.