Everyone's dream came true when the "High School Musical" cast reunited for the film's 10th anniversary party. We already got a glimpse of Vanessa Hudgens, Ashley Tisdale, Corbin Bleu and Lucas Grabeel but it was pretty hard to miss Zac Efron's absence.

'High School Musical' Stars Reunite To Celebrate Their 10th Anniversary

The Neighbors actor reportedly couldn't make it because he has too many commitments. However, new reports surface about Vanessa Hudgens threatening to back out should her ex show up in the reunion.

A source told Hollywood Life: "Vanessa and Zac are on bad terms and they don't want to see each other. Things would be awkward and there would be a lot of issues that would come up and they wouldn't feel comfortable faking it in front of cameras," the source said.

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"They had a horrible breakup and she really doesn't want to hear his name let alone be in the same room with him. To say she was relieved he wasn't there is an understatement. She probably wouldn't have done it had he confirmed showing up for it."

HSM fans took to Twitter to express their frustration towards Efron's absence.

Well, when you think about it, it's not really a reunion without Troy Bolton, right?