When updating to mariadb 11.5, the file /usr/sbin/mysqld was lost. I tried to find it but still couldn't find it.what errors was during compilation? looks like it lack main file /usr/sbin/mysqld
MariaDB is designed to allow easy upgrades.
You should be able to trivially upgrade from ANY earlier MariaDB version to the latest one
(for example MariaDB 10.3.x to MariaDB 10.11.x)