Failed Upgrade (Zabbix 5.0.4 -> 5.4)

[BlakeD]

Novice user, mostly use Zabbix for monitoring stuff on my home network.
OS: Ubunta 18.04
Zabbix: 5.0.4 upgrading to 5.4

Went through the upgrade process documented here (https://www.zabbix.com/documentation.../debian_ubuntu)
After upgrade completed, I received the following error after restarting the service:

Database error

• The Zabbix database version does not match current requirements. Your database version: 5030069. Required version: 5040000. Please contact your system administrator.

Examining the zabbix_server.log, I find the following:

7989:20210519:100009.216 Zabbix Server stopped. Zabbix 5.0.4 (revision 69c0ad3686).
19641:20210519:100503.547 Starting Zabbix Server. Zabbix 5.4.0 (revision 5059e20a75).
19641:20210519:100503.547 ****** Enabled features ******
19641:20210519:100503.547 SNMP monitoring: YES
19641:20210519:100503.547 IPMI monitoring: YES
19641:20210519:100503.547 Web monitoring: YES
19641:20210519:100503.547 VMware monitoring: YES
19641:20210519:100503.547 SMTP authentication: YES
19641:20210519:100503.547 ODBC: YES
19641:20210519:100503.547 SSH support: YES
19641:20210519:100503.547 IPv6 support: YES
19641:20210519:100503.547 TLS support: YES
19641:20210519:100503.547 ******************************
19641:20210519:100503.547 using configuration file: /etc/zabbix/zabbix_server.conf
19641:20210519:100503.583 Unsupported DB! MariaDB version is 50505 which is smaller than minimum of 100037
19641:20210519:100503.593 current database version (mandatory/optional): 05000000/05000002
19641:20210519:100503.593 required mandatory version: 05040000
19641:20210519:100503.593 starting automatic database upgrade
19641:20210519:100503.963 completed 0% of database upgrade
19641:20210519:100504.234 completed 1% of database upgrade
...
19641:20210519:100524.483 completed 51% of database upgrade
19641:20210519:100524.495 [Z3005] query failed: [1832] Cannot change column 'scriptid': used in a foreign key constraint 'c_opcommand_2' [alter table opcommand modify `scriptid` bigint unsigned not null]
19641:20210519:100524.495 database upgrade failed

[BlakeD]

And this one does not bother you ? "19641:20210519:100503.583 Unsupported DB! MariaDB version is 50505 which is smaller than minimum of 100037"

As I started off the post with saying, novice user. I saw that, but I also saw the subsequent lines:

19641:20210519:100503.593 starting automatic database upgrade
19641:20210519:100503.963 completed 0% of database upgrade
19641:20210519:100504.234 completed 1% of database upgrade

I interpreted that to mean the upgrade script recognized the need to upgrade maria and was doing so. Somewhere in the script's process (whatever occurs at 51%), it errored out. Exactly what is transpiring at that point in the process, I have no clue as it is obfuscated by the simple "completed xx% of database upgrade". I thought someone here might know what's occurring around that time of the upgrade, and therefore might be able to suggest possible causes for failure during that phase of the operation. And if nothing else, since I'm the second user with a nearly identical environment to report this exact error when following the DOCUMENTED upgrade process, I thought someone might like to know so they can fix the documentation or investigate to see if there's a bug that needs correcting.

I don't know. Maybe I was naïve and idealistic.

[cyber]

And this one does not bother you ? "19641:20210519:100503.583 Unsupported DB! MariaDB version is 50505 which is smaller than minimum of 100037"

[cyber]

These database upgrade messages are about DB structure changes, adding, removing, converting etc. This will never upgrade the version of DB. This is something that has to be done beforehand, preparing platform to meet requirements.
TBH, If it would be my decision to create that upgrade script, I would not go on with upgrade, when discovering unmet requirements... would have caused less mess in this case.Maybe it should be reported as a bug...