报错：The Zabbix database version does not match current requirements. Your database version: 5000000. Required version: 4000000. Please contact your system administrator.

问题原因：
当前数据库版本与所需数据库版本不一致；
解决方法：
登录数据库，修改数据库版本的mandatory值至4000000

MariaDB [(none)]> use zabbix;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
MariaDB [zabbix]> select version();
+----------------+
| version()      |
+----------------+
| 5.5.68-MariaDB |
+----------------+
1 row in set (0.00 sec)

MariaDB [zabbix]> update dbversion set mandatory=4000000;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

MariaDB [zabbix]> flush privileges;
Query OK, 0 rows affected (0.00 sec)

MariaDB [zabbix]> select version();

重启zabbix-server端即可