As more and more reviewers were given early viewings, rumors began to fly this week that Toy Story 4 would be released without the traditional Pixar original short film. Only two of the 21 feature films have done so: Pixar's first, Toy Story, before the tradition had been established, and Coco which came temporarily joined at the hip with Disney-made short, Olaf’s Frozen Adventure, which was eventually pulled from theaters due to negative feedback from viewers (lest we forget).
This was later confirmed by Pixar producers, Jonas Rivera and Mark Nielsen. “The people at the studio were all needed to work on feature films at the time. There was a big demand to finish up the last few films, and there just wasn’t the people to make a short.”
The insist that this is only a temporary circumstance, and shorts will return in the future. No word yet as to whether that will be with Pixar's next feature, Onward.