Plugin ‘SPIDER’ registration as a STORAGE ENGINE failed.

I fixed a stupid error which had me stumped. Here’s the answer for posterity:

mysql_upgrade

I was doing this on mariadb to install the spiderdb engine, and it was not working:

MariaDB [(none)]>  install plugin spider soname 'ha_spider';
ERROR 1123 (HY000): Can't initialize function 'spider'; Plugin initialization function failed.

The .so file was present, and there’s really no reason for it to fail. Since I couldn’t find the log file, I was stumped … it was hiding away in /var/lib/mysql/$(hostname).err and saying:

2019-08-12 18:35:51 10 [ERROR] Column count of mysql.proc is wrong. Expected 21, found 20. Created with MariaDB 50541, now running 100407. Please use mysql_upgrade to fix this error
[ERROR] Column count of mysql.proc is wrong. Expected 21, found 20. Created with MariaDB 50541, now running 100407. Please use mysql_upgrade to fix this error
2019-08-12 18:35:51 9 [ERROR] Plugin 'SPIDER' init function returned error.
2019-08-12 18:35:51 9 [ERROR] Plugin 'SPIDER' registration as a STORAGE ENGINE failed.

And then I remembered that this is an installation that was upgraded from previous versions a few times over – and after running mysql_upgrade to create the table that says what plugins are enabled, it worked just great:

MariaDB [(none)]>  install plugin SPIDER soname 'ha_spider';
 Query OK, 0 rows affected (0.075 sec)