https://www.zabbix.com/documentation/4.2/manual/installation/upgrade/packages/debian_ubuntu says that "Zabbix server and proxies must be of the same major version." but https://www.zabbix.com/documentation/4.2/manual/appendix/compatibility says "Zabbix 4.2.x server can only work with Zabbix 4.2.x proxies"

This means that the server and proxies must be of the same minor version.