UFC 234 takes place at Rod Laver Arena in Melbourne, Australia. He's fought hard to get to a title shot, and it's understandable he would be a little miffed at this last-minute pullout from Whittaker.
It's a huge blow to Whittaker, 28, who was forced to pull out of a title defense on home soil in February 2018.
UFC's rising star Israel Adesanya (15-0) and Anderson Silva (34-8) will now headline UFC 234, with the victor promised a shot at the title later in the year although now with Whittaker off the card the potential date is uncertain.
Because his next fight against Yoel Romero was a non-title bout after Romero missed weight, Whittaker still has yet to officially defend his belt a year into his status as middleweight champ.
Per Okamoto, the hernia was not related to Whittaker's weight cut.
With next to no time to find a replacement for Whittaker all the way out in Australia, UFC 234 turned to its old superstar in Silva to headline the event.
UFC 234 has been plunged into turmoil by Robert Whittaker's injury exit on Saturday night.
"The Ultimate Fighter 17" victor has been working for a chance at UFC gold for a long time.
Elevated to the co-main is the lightweight matchup between American Lando Vannata and Brazilian Marcos Mariano.
There are a total of five fights on the main card.