The Articles of Confederation were far too weak to meet the needs of the newly created United States because of the massive decentralization the Articles contained.
They did not give the government any right to tax the people, and had to ask the states for taxes, and the states were not keen to pay them unless it benefited them. Often found were states not contributing to the pay of the Continental Army because it was not in their territory and defending them. This was also the reason Valley Forge was a disastrous winter for the Continental Army.
The Constitution fixed this by mandating budgets and making sure the states did in fact pay dues to the Gov't, later amended with (the supposed temporary) Federal income tax, starting after The Great War.
The other big failure is the lack of a requirement delegates be there, and the fact it requires every state to vote yes, an amendment to let the Confederation place import taxes to help pay the army was a washed failure because Rhode Island feared having their economy impacted horribly as they were so small they only had trade.
The New Constitution fixed this by making it so 3/4 of the states had to vote Aye to an amendment to the Constitution itself, and made the Federal Government itself handle passes legislation at it's own level with a majority rules, rather than all.
A four episode series from Extra History delve with a good amount of detail as to the Articles' other short comings, and what I elaborated on. Would strongly recommend a watch: https://youtu.be/C6rHSiN0vKk
