For those saying that they got no warning, Discord and Nutaku warned us all that the update was happening today, for ten hours. If you're expecting to be compensated because you forgot/didn't know/didn't care and now you're upset because you missed a few gathers, that's kinda silly. It's a ten hour maintenance, and they told us it was going to be that long when they announced it for last week with only a day or two of notice. Now you've had a week to prepare for today's maintenance. We all lost some stamina regeneration time and some gathers because of the gargantuan down time, but to say the devs sprung this on us is false.
And as for the reissued Canna event, you should have one more day/a dozen or so hours after today's downtime to finish your farming.
I personally finished up my alt's event grinding yesterday instead of Manyu farming because I knew I'd have limited time to use my Stamina on the Dragon Farming before the maintenance, so I planned accordingly. Finished the event, got my 6 yellow level 100 Dragons in my early runs, and finished up my Stam bar about ten minutes before the maintenance came on. Those who are complaining it's BS are kinda... just being childish.
/endrant
Sorry if the text wall seems rude.
tl;dr: Dev's warned us don't expect to be compensated because you forgot big maintenance was today.