One major flaw was that the federal government could not tax citizens. Without taxation the government gets no money and thus cant provide services such as a national guard. There was no way for the government to respond to Shays' rebellion.
There was only one house of delegates and amendments made had to be done with a unanimous decision from all the states. Every state had only one vote, regardless of size. Congress did not have the power to regulate foreign and interstate commerce. There was no uniform system system of currency, some states were different.
It was difficult for congress to pass laws, they needed a 9/13 vote. Also it gave no central leadership to enforce these laws. The Articles were purposely written to keep the national government as weak as possible. The national government was powerless to enforce any acts it did pass. The Articles of Confederation were a big failure.
