don't?
https://ronconte.wordpress.com/2012/06/04/the-day-of-the-crucifixion-friday-nisan-14/
The Passover meal is eaten after sunset on Nisan 14. But since the Jewish day begins at sundown, the meal is eaten at the start of Nisan 15. When Nisan 14 falls on a Friday, the meal is eaten on Friday, after sunset (which the Jews consider to be the start of Saturday).
John’s Gospel implies that Jesus died on a Friday, by saying:
{19:31} Then the Jews, because it was the preparation day, so that the bodies would not remain upon the cross on the Sabbath (for that Sabbath was a great day), they petitioned Pilate in order that their legs might be broken, and they might be taken away.
The Sabbath (Saturday, beginning Friday at sunset) was a great day because it was both the Sabbath (Saturday) and the first day of Passover (Nisan 15). This implies that Jesus died on Friday, Nisan 14, before sunset.
The synoptic Gospels do not contradict this chronology. They each and all assert that Jesus died on a Friday, at the start of Passover. However, an apparent contradiction results from the fact that Jesus and His disciples at the Passover meal the previous evening, on Thursday after sunset (which technically is the start of Friday in the Jewish calendar). The assumption is made that Jesus ate the Passover on Nisan 14, but this is never stated by the synoptics. There is no contradiction or error in any of the Gospels on this point of chronology, if Jesus ate the Passover a day earlier than most Jews.
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There is no contradiction between the synoptic Gospels and the Gospel of John. Jesus and His disciples celebrated the Passover meal a day early, on Thursday evening. Divine Providence arranged events so that Jesus could both celebrate the Passover supper with His disciples on Thursday evening and also be the Passover Lamb sacrificed on the Cross on Friday. Only those who are lacking in faith will believe that any part of Sacred Scripture could ever be in error.
Therefore, Jesus was crucified on Friday, Nisan 14, before sunset. He ate the Passover meal on the previous evening (Thursday), which the Jews consider to be the same day (Friday), since their day begins at sunset.