There are a number of crises that contributed to this reckoning.  Three of the most important are:

• The Black Death.  This plague, of course, killed a huge percentage of the population of Europe.  It lead to serious disruptions in society and the economy.
• The 100 Years War.  This war caused the devastation of many areas in France.  It also helped to impoverish people as kings demanded taxes from their subjects to pay for the war.
• The Great Schism.  This was the time when there were two (or even more) popes at one time.  This helped to weaken the people's faith in the Church.

In this way, huge crises hit Europe late in the Middle Ages.  They affected society, the economy, and even people's sense of religious faith.