Accordinf to the standard narrative, Ramadan had always coincided with the Advent Fast and Eid ulAzhar had always coincided with Palm Sunday until 632. But following 12 Lunar Months the calendar had slipped forward two whole months against the Solar year by the time Umar's came to power in 634.
===Uthman's Mushaf===
According to the standard narrative, Uthman ordered all Quranic materials to be burned except for the "Quraysh" version written by Zaid ibn Thabit. He also killed the supporters of Ibn Mansur who opposed his decision.