The migration has now completed.
I am pleased to confirm the outage was indeed minimal, at just a few minutes.
Thanks for your patience - the issues with MySQL / MariaDB incompatibility are now resolved.
We are now carrying out the migration from the old hardware, to the new kit as an emergency prodedure.
Downtime is to be expected throughout this phase, although we hope to keep downtime to a minimum.
The service is now back online. Unfortunately, the downgrade didn't complete successfully, which does mean we are still running MariaDB 10.4 at present, which is technically unsupported.
Due to the incompatibility, our recommendation at this point would be for us to arrange for your accounts to be migrated to a new server, in place of the current server. There would be an IP address change in doing so, but no downtime should be required if you are using our nameservers (for any sites using external DNS, such as Cloudflare, you would need to update the IP address).
The preferable option moving forward, would be for clients to request migration to move to alternative hardware.
As planned, we attempted the full server migration, however there were significant delays in migration of the MySQL data.
This caused us to halt the migration process.
Due to emergency demand, we are attempting a live downgrade of the MySQL service currently, however expected downtime will be approx 1 hour.
We will update here once the attempt has been completed.