Update 3:07 PDT: Season of Blood has just been launched and it's now available to play, so the delay has been indeed quite brief.
You can read the original article below.
The announcement, which came pretty much at the last possible moment since the season was scheduled to launch today, mentions that the developers have encountered unspecified "technical issues"
Luckily, it appears that the delay won't be massive, and we're looking at just a few hours.
We have encountered some technical issues with our current build and will be delaying Season of Blood’s start time by a few hours to remedy these issues. Once we have more information, we’ll update you right away. We apologize for the inconvenience and appreciate the feedback you have provided and your patience."
At the moment, we don't know when the season will actually be launched, but we'll update this article as soon as Blizzard announces something new.
Incidentally, Diablo IV is also releasing on Steam today, but there is no indication that the launch on Valve's digital storefront is affected by the delay.
Season of Blood will bring a new storyline to the game and will let players become infected by a vampiric curse and acquire powerful vampiric abilities. They will be tasked to aid the vampire hunter Erys (voiced by Gemma Chan) in countering the vampiric invasion.
When I say "Invasion" I mean it quite literally, as we'll have to fight plenty of new monsters controlled by a powerful vampire named Lord Zir.
There will also be a roaming event named "Blood Harvest" that will see vampires overwhelm whole areas of the map, and defeating them will net plenty of Potent Blood, which is the key to unlocking the vampiric powers mentioned above.
Diablo IV is currently available for PC via Battle Net, PS5, PS4 Xbox Series X|S, and Xbox One. If you'd like to read more, you can check out our review.