You can install KUMA 1.6.x over versions 1.5.x. To do this, follow the instructions for installing the program in a production environment, and when you reach the stage of preparing the inventory file list the hosts of the already deployed KUMA system in it.
After updating KUMA to version 1.6, event filtering that uses an SQL query containing the inSubnet condition may result in error Code: 441. DB::Exception: Invalid IPv4 value. If this is the case, you must add the directive <cast_ipv4_ipv6_default_on_conversion_error>true</cast_ipv4_ipv6_default_on_conversion_error> in the profiles → default section of the file /opt/kaspersky/kuma/clickhouse/cfg/config.d/users.xml on the storage servers (on each machine of the ClickHouse cluster).