From now on values older than the configured history and trend storage period will be rejected, even if the internal housekeeping is disabled. You may want to adjust history/trend storage periods after the upgrade.
Parameters for encrypting the connection between frontend and the database, available during Zabbix frontend installation, have been modified. The Configure DB connection step of Zabbix web interface now features a new checkbox Verify certificate with additional options appearing upon marking it. Parameters that are unavailable in the particular configuration will be disabled. For example, the Database TLS encryption checkbox cannot be checked if using MySQL and Database host is set to localhost. See Secure connection to the database page for the full description.
The SourceIP configuration parameter is now used for webhooks.
See the list of API changes in Zabbix 5.0.5.