What did king john do that led to an uprising among englands nobles?

He executed a noble man and demanded people to pay extra high taxes. 

 Shay's rebellion was important to highlight the problems with the Articles of Confederation because it showed the people and government how terrible the Articles couldn't handle a crisis. 

 Many of the poorer people had to take large loans to keep their farms functioning while they were off fighting in the revolution. When the war ended, they had no money to pay the creditors back, who began pressing for the money. 

I hope this helps.