Why Was John wycliffe not popular with the leaders of the Roman Catholic Church?

Because Rome had demanded financial support from England, a nation struggling to raise money to resist a possible French attack. Wycliffe advised his local lord, John of Gaunt, to tell Parliament not to comply. He argued that the church was already too wealthy and that Christ called his disciples to poverty, not wealth. If anyone should keep such taxes, it should be local English authorities.

Such opinions got Wycliffe into trouble, and he was brought to London to answer charges of heresy. The hearing had hardly gotten underway when recriminations on both sides filled the air. Soon they erupted into an open brawl, ending the meeting. Three months later, Pope Gregory XI issued five bulls (church edicts) against Wycliffe, in which Wycliffe was accused on 18 counts and was called "the master of errors."

John Wycliffe left quite an impression on the church: 43 years after his death, officials dug up his body, burned his remains, and threw the ashes into the river Swift. Still, they couldn't get rid of him. Wycliffe's teachings, though suppressed, continued to spread. As a later chronicler observed, "Thus the brook hath conveyed his ashes into Avon; Avon into Severn; Severn into the narrow seas; and they into the main ocean. And thus the ashes of Wycliffe are the emblem of his doctrine which now is dispersed the world over."