This was not the first time Gastelum has been unable to make weight head of a bout scheduled at 170 pounds.
Gastelum had missed weight twice previously including one occasion where he faced current welterweight champion Tyron Woodley and came in nine pounds over the allotted limit. Following that fight, Gastelum was forced to move to middleweight for one bout before the UFC allowed him to try welterweight again.
Since then, Gastelum had gone 1-1 without missing weight, but this latest incident has forced the UFC to insist that he no longer competes in the 170-pound division.
Cerrone, one of the UFC's most active fighters, has now been touted to face Matt Brown at UFC 206 in Toronto on December 10 (December 11 AEDT).
Another situation unfolded early Friday morning (US time), when Thiago Alves stepped on the scale at 162.6 pounds for his lightweight debut.
Because Alves weighed in first, his opponent Jim Miller was allowed to rehydrate before coming in at 157.6, which was within the five pound allowance. Alves was fined 20-percent of his purse for missing weight.
Alves will not be allowed to weigh more than 173 pounds when he checks in for his fight on Saturday per an agreement made between the UFC and Miller's team.
It was a matter of unfortunate timing for Cerrone, who hit the scale ahead of his opponent, which meant Gastelum had to be within five pounds of his recorded weight - 170.4 - to allow the fight to move forward. Gastelum clearly knew he wasn't going to get down to that weight allowance so he didn't even step onto the scale.
With "Cowboy" vs. Gastelum off, the UFC 205 main card will now move forward with five fights on pay-per-view.
All of the other fighters on the card made weight without incident including the main event bout between lightweight champion Eddie Alvarez and featherweight king Conor McGregor.
Alvarez was the first to step onto the scale, making weight at 154.6 pounds. McGregor followed a few minutes later and hit 154.4 pounds for his first lightweight bout in the UFC as he looks to become the first ever simultaneous two division champion in the promotion's history.
There was no drama for either of the other title fights with Tyron Woodley and Stephen "Wonderboy" Thompson both coming in at championship weight while strawweight queen Joanna Jedrzejczyk and top contender Karolina Kowalkiewicz both weighed an identical 114.4 pounds.
Ronaldo "Jacare" Souza was also on hands for the weigh-ins as an alternate just in case either Chris Weidman or Yoel Romero were unable to compete this weekend. Souza weighed in at 189 pounds and will be compensated for his time.
