What were three difficulties caused by the Articles of Confederation?

One difficulty was a major fiscal crisis confronting the new nation. Both the states and the national government had enormous debts from the Revolutionary War. The problem was that under the Articles of Confederation, the national government essentially lacked the power to tax. Therefore it could not raise enough money to service the national debt, and could not inspire much confidence among potential creditors among the nations of Europe. 

Another problem was the lack of...

One difficulty was a major fiscal crisis confronting the new nation. Both the states and the national government had enormous debts from the Revolutionary War. The problem was that under the Articles of Confederation, the national government essentially lacked the power to tax. Therefore it could not raise enough money to service the national debt, and could not inspire much confidence among potential creditors among the nations of Europe. 

Another problem was the lack of unity in dealing with foreign affairs. The British were quick to exploit this weakness by maintaining forts on the American frontier in contravention of the Treaty of Paris that had ended the Revolutionary War. Spanish influence among Western settlers was also seen as a problem, and farmers who moved west of the Appalachian worried that they couldn't ship their produce down the Mississippi River, as Spain controlled the city of New Orleans. There was little the national government, which couldn't really raise an army, and which totally lacked diplomatic clout, could do about it.

Finally, in the absence of a central authority with the sole power to regulate interstate commerce, many of the states levied tariffs on each other's goods, a potentially ruinous development. This created enormous animosity between many of the states, and was, in fact, was one of the reasons that the first meetings of state delegates was called at Annapolis, Maryland one year before the Philadelphia Convention.