Thanks Roy Kaldung for answer directly. I won't take too much of your time. Once again, nothing I'm doing here is urgent - the production instance is fine; I'm working on a dev box and I make a database dump before and after each upgrade, so I can blow it up as many times as I want and can always roll back with no worries. I got the instance upgraded to 3.2 successfully Saturday night. On Sunday I attempted an upgrade to 3.3 on the same Ubuntu 12.04 box I set up and the database update failed on constraint creation. The problems on the old box were a mix of InnoDB and MyIsam storage on different tables, and different charsets and collations, some of the old latin1_swedish_ci. So I set up another box with Ubuntu 18.04LTS with MariaDB on it, set InnoDB as the default storage engine, utf8 as charset for client, connection, database, results, server, and system, and utf8_general_ci as collation for connection, database, and server, all verified by showing the variables. I then restored the post 2.2 upgrade database. Then I proceeded to do a regular upgrade. DBUpdate-to-3.3.sql ran clean. The resulting DB shows InnoDB for all tables and utf8_general_ci as the collation for all the tables except for the following, which I checked and are explicitly created with utfmb4_unicode_ci collation from the dump script create table statements. (this is for info only - None of these tables are involved in the error in step 7) article pm_activity pm_activity_dialog pm_entity pm_entity_sync pm_process pm_transition pm_transition_action sessions Once everything else checked out I attempted once more to run DBUpdate-to-3.3.pl Steps 1-6 done - no issues. Steps 8-13 done - no issues (except the Subroutine Load redefined - no need to worry message in 13 of 13). Back to step 7 - here are results ******************** results start ***************** Step 7 of 13: Updating Queue Standard Template relations table... Cleaning queue_standard_template table Creating new Foreign Keys for queue_standard_template table --- Note: --- If you have already run this script before then the Foreign Keys are already set and you might see errors regarding 'duplicate key' or 'constrain already exists', that's fine, no need to worry! --- ALTER TABLE queue_standard_template ADD CONSTRAINT FK_queue_standard_template_standard_template_id_id FOREIGN KEY (standard_template_id) REFERENCES standard_template (id) ALTER TABLE queue_standard_template ADD CONSTRAINT FK_queue_standard_template_queue_id_id FOREIGN KEY (queue_id) REFERENCES queue (id) [Mon Feb 18 15:09:28 2019] DBUpdate-to-3.3.pl: DBD::mysql::db do failed: Cannot add or update a child row: a foreign key constraint fails (`otrs33`.`#sql-337c_22`, CONSTRAINT `FK_queue_standard_template_queue_id_id` FOREIGN KEY (`queue_id`) REFERENCES `queue` (`id`)) at /opt/otrs/Kernel/System/DB.pm line 493. ERROR: OTRS-DBUpdate-to-3.3-10 Perl: 5.26.1 OS: linux Time: Mon Feb 18 15:09:28 2019 Message: Cannot add or update a child row: a foreign key constraint fails (`otrs33`.`#sql-337c_22`, CONSTRAINT `FK_queue_standard_template_queue_id_id` FOREIGN KEY (`queue_id`) REFERENCES `queue` (`id`)), SQL: 'ALTER TABLE queue_standard_template ADD CONSTRAINT FK_queue_standard_template_queue_id_id FOREIGN KEY (queue_id) REFERENCES queue (id)' Traceback (13267): Module: main::_AddQueueStandardTemplateForeignKeys (unknown version) Line: 556 Module: scripts/DBUpdate-to-3.3.pl (unknown version) Line: 132 ERROR: OTRS-DBUpdate-to-3.3-10 Perl: 5.26.1 OS: linux Time: Mon Feb 18 15:09:28 2019 Message: Error during execution of 'ALTER TABLE queue_standard_template ADD CONSTRAINT FK_queue_standard_template_queue_id_id FOREIGN KEY (queue_id) REFERENCES queue (id)'! Traceback (13267): Module: main::_AddQueueStandardTemplateForeignKeys (unknown version) Line: 559 Module: scripts/DBUpdate-to-3.3.pl (unknown version) Line: 132 done. ******************** results end ******************** I ran Show Create Table queue_standard_template; to see if the FK Constraints took, with the following results: | queue_standard_template | CREATE TABLE `queue_standard_template` ( `queue_id` int(11) NOT NULL, `standard_template_id` int(11) NOT NULL, `create_time` datetime NOT NULL, `create_by` int(11) NOT NULL, `change_time` datetime NOT NULL, `change_by` int(11) NOT NULL, KEY `FK_queue_standard_response_queue_id_id` (`queue_id`), KEY `FK_queue_standard_response_standard_response_id_id` (`standard_template_id`), KEY `FK_queue_standard_response_create_by_id` (`create_by`), KEY `FK_queue_standard_response_change_by_id` (`change_by`), CONSTRAINT `FK_queue_standard_template_standard_template_id_id` FOREIGN KEY (`standard_template_id`) REFERENCES `standard_template` (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 | Just to verify I ran a select statement to return all constraints: MariaDB [otrs33]> select COLUMN_NAME, CONSTRAINT_NAME, REFERENCED_COLUMN_NAME, REFERENCED_TABLE_NAME -> from information_schema.KEY_COLUMN_USAGE -> where TABLE_NAME = 'queue_standard_template'; +----------------------+----------------------------------------------------+------------------------+-----------------------+ | COLUMN_NAME | CONSTRAINT_NAME | REFERENCED_COLUMN_NAME | REFERENCED_TABLE_NAME | +----------------------+----------------------------------------------------+------------------------+-----------------------+ | standard_template_id | FK_queue_standard_template_standard_template_id_id | id | standard_template | +----------------------+----------------------------------------------------+------------------------+-----------------------+ 1 row in set (0.00 sec) If I'm reading the results correctly I'm missing one constraint on the queue_id table. The first constraint , FK_queue_standard_template_standard_template_id_id appeared to apply correctly. But the second constraint here did not apply: ALTER TABLE queue_standard_template ADD CONSTRAINT FK_queue_standard_template_queue_id_id FOREIGN KEY (queue_id) REFERENCES queue (id) If correctly applied the results should read: ----------------------+----------------------------------------------------+------------------------+-----------------------+ | COLUMN_NAME | CONSTRAINT_NAME | REFERENCED_COLUMN_NAME | REFERENCED_TABLE_NAME | +----------------------+----------------------------------------------------+------------------------+-----------------------+ | standard_template_id | FK_queue_standard_template_standard_template_id_id | id | standard_template | +----------------------+----------------------------------------------------+------------------------+-----------------------+ | standard_template_id | FK_queue_standard_template_queue_id_id | id | queue | +----------------------+----------------------------------------------------+------------------------+-----------------------+ Bottom line: It looks like I either need to simply add the second constraint or I need to add the Key FK_queue_id and then add the constraint, which means I can fix the issue with one or two SQL statements. if this is correct, all I should need is the proper syntax of the one or two statements, then the database should be good to go. Kind regards, Rob Mitchell