Why didn't Mashiah come Pesah 1990?
Hashem1.net links to a video from Rav Mutzafi who retells what happened before Pesah 1990.
Rav Ben-Tzion Abba Sha'ul, Zt"l, the famed Rosh Yeshiva of Yeshivat Porat Yosef, had mentioned before Pesah that year that there would be a great chance of Mashiah coming that Pesah. He even told those close to him to cancel flights going out of Israel.
However, when Pesah arrived and he had not come, and it soon became clear that he wasn't coming even close to Pesah, 2 Talmidei Hachamim started to wonder why his prediction had not come true, and indirectly asked the rabbi why Mashiah hadn't come.
Rav Abba Sha'ul answered that really Mashiah was supposed to come at that time. However, something occurred that was so grave that it destroyed everything that was built up at that time and therefore postponed Mashiah's arrival.
The Talmidei Hachamim reluctantly asked what it was that postponed Mashiah's arrival. Rav Abba Sha'ul replied that it was the contempt for Rav Ovadia Yosef, Shlit"a, that was displayed a bit before Pesah that year. That display of contempt was so grave in the eyes of Heaven that it was decided to subsequently cancel Mashiah's arrival for that time period. (Rav Mutzafi heard this story from the Talmidei Hachamim.)
What a terrible missed opportunity!!!
The Gemara in Shabbat 119b says that Yerushalayim was destroyed only because they were Mevazeh Talmidei Hachamim within it.
For more on Bizui Talmidei Hachamim, see these videos from Rav Zer and this post.