cannot INSTALL SONAME 'ha_sphinx';

I have a 10.1.26 docker alpine container based on a previous version of Johan Bergström working with sphinx (on docker hub kklepper/mariadb33).

In order to upgrade, I adopted the new version of Johan (kklepper/mariadb33-10.4.18) in which I cannot activate the sphinx plugin:

M:2521920 [(none)]>INSTALL SONAME 'ha_sphinx';

ERROR 1126 (HY000): Can't open shared library '/usr/lib/mariadb/plugin/ha_sphinx.so' (errno: 13, Error relocating /usr/lib/mariadb/plugin/ha_sphinx.so: _ZNK30Type_handler_hybrid_field_type26get_handler_by_result_typeE11Item_r)

Unfortunately, this plugin is crucial for my application, so I have to fix this.

The error message is enigmatic for me, however, and I have no idea of how to debug this.

I added ha_sphinx.so to /usr/lib/mariadb/plugin/ manually. The original file is indeed present at the given path and file privileges do not matter.

The former image features 36 plugins. I had to manually add ha_sphinx.so in previous versions, so I guess the appropriate alpine package had been augmented.

What can I do to resolve this problem? Is it a problem of MariaDB or of the alpine package involved?