Setting the below works as expected for 10.6 (despite being 10.5) and enables forward-looking customers to prepare their configuration files for a future 10.6+ upgrade-

[server]

character_set_server=utf8mb3

At runtime, the server detects-

SELECT @@character_set_server, @@collation_server;

+------------------------+--------------------+

| @@character_set_server | @@collation_server |

+------------------------+--------------------+

| utf8                   | utf8_general_ci    |

+------------------------+--------------------+

However, when configuring the MariaDB CLI client like-

[client]

default_character_set=utf8mb3

The below error occurs when invoking mariadb-

ERROR 2019 (00000): Can't initialize character set utf8mb3 (path: compiled_in)

Note this also occurs for-

mariadb --default-character-set='utf8mb3'

Please note these CLI configurations work fine in Server 10.6.5.

Would it be possible to backport enablement of this from 10.6 to 10.5 (and any other versions for which character_set_server=utf8mb3 is valid syntax?

This is particularly important for MariaDB client configurations. While server configurations tend to be centralized to the MariaDB backend servers and managed by dedicated teams, client configurations and runtime parameters tend to be much more decentralized, and it can take significant time for client organizations to wrangle these into spec. By enabling 10.6+ syntax for client configurations in versions prior to 10.6, customers can start this process now, making them better prepared to move to 10.6, and even better prepared to handle what occurs when we inevitably change the default character set defined by utf8 from utf8mb3 to utf8mb4.