Hi,
After completing the instructions here
https://docs.nextcloud.com/server/15/admin_manual/configuration_database/mysql_4byte_support.html
I get these results:
show variables like 'innodb_file_format';
innodb_file_format | Barracuda
and …
SELECT NAME, SPACE, FILE_FORMAT FROM INFORMATION_SCHEMA.INNODB_SYS_TABLES WHERE NAME like "nextcloud%";
MariaDB reports Barracuda on all tables. 
However. Nextcloud/settings/admin/overview still says…
MySQL is used as database but does not support 4-byte characters. To be able to handle 4-byte characters (like emojis) without issues in filenames or comments for example it is recommended to enable the 4-byte support in MySQL. For further details read the documentation page about this.
Server versions are:
Nextcloud version (15.0.10):
Operating system and version (Debian Jessie):
Apache or nginx version (nginx/1.10.2):
PHP version (7.0.31-1):
Mariadb version (10.0.29-MariaDB-0+deb8u1):
I would like to resolve this before updating nextcloud, and then move the instalation to a new server.
Could someone please point me in the right direction?
Thanks.
Chris.