Item descriptions have been fixed in the following templates:
In order to fix it, import these templates from https://www.zabbix.org/wiki/Zabbix_Templates/Official_Templates.
Support for PHP mutexes has been removed on the server side due to licensing issues. While it was not recommended to use Zabbix server and frontend with SQLite3 database before, this change makes it even less recommended, because simultaneous database access with Zabbix server and frontend may now corrupt the database. Note that using Zabbix proxy with SQLite3 database is still a perfectly valid solution.