https://www.zabbix.com/documentation/5.0/manual/installation/upgrade_notes_500#enabling_extended_range_of_numeric_float_values says:

Make sure Zabbix server is stopped before running these scripts. Restart the server afterwards.

This is slightly confusing, as usually "restarting" in service context implies restarting a running service.
Perhaps the second sentence should be removed, or changed to "Start the server afterwards".