What famous event proved that the Articles of Confederation were weak and prompted the Constitutional Convention? What happened during this event?

Daniel Shays was a farmer in Massachusetts and a veteran of the Revolutionary War. He was owed money by the US Government for his service in the Continental Army.

Here's the problem: the US Government had precisely zero ability to raise money through taxes. (After all, what was one of the major problems that caused colonists to fight against the British? Wait for it....taxes! More precisely, a lack of representation in the levying of taxes.) Only states were allowed to raise taxes.

Here comes the next problem. Guess who was taxing Daniel Shays? That's right: Massachusetts.

So Shays owed Massachusetts money, which he could not pay because of a poor harvest on his farm and the debt owed him by the US. Massachusetts seized his farm.

Shays was suitably angry and led a rebellion of other similarly upset Massachusetts farmers. The rebellion was put down, but not without several people dying. Shays survived, but he had to flee to Vermont.

How does this all wind up coming back to the Articles? Well, primarily because it became a wake up call ... not because of the fact that the US owed people who served in the army money and spurred them on to rebellion, but, rather, it woke people up to the fact that there was a very real possibility of another revolution, and a central government too weak to do anything about it. And, of course, there were other conflicts brewing between states regarding interstate commerce, and the US once again had no power to do anything about it, by design, because of the way the Articles were created.