Melanie Calvat (seer at La Salette):
"The Church will be eclipsed. At first, we will not know which is the true pope. Then secondly, the Holy Sacrifice of the Mass will cease to be offered in churches and houses; it will be such that, for a time, there will not be public services any more. But I see that the Holy Sacrifice has not really ceased: it will be offered in barns, in alcoves, in caves, and underground." (Abbot Combe: "The Secret of Melanie and the Actual Crisis", Rome, 1906, p. 137)
She even lays out the sequence.
1) true Pope is not known (1958)
2) Holy Sacrifice will cease and be exiled from the churches (1969)