The control of commerce.
The various states felt that they were independent of one another and had the right to tax goods of other states coming into their ports or across their borders. When Virginia asserted the right to seize vessels from other states as well as other countries that did not pay its import taxes, it became apparent that something had to be done. At first members of the states met in the Annapolis Convention to discuss commerce among the states, but it soon became apparent that no state wanted to relinquish its sovereignty. Congress then called for a convention ". . . for the sole and express purpose of revising the Articles of Confederation."
Another incident was Shays' Rebellion in 1786 where citizens rebelled against taxation by the government of Massachusetts. George Washington was appalled that the federal government was powerless to stop such a rebellion that was almost exactly like the American Revolution, in which colonials rebelled against taxation by Great Britain.
At the Constitutional Convention, the most significant disagreement dealt with the issue of representation in the legislature. The convention was held in 1787.
Represntation
Constitutional convention deadlocked over the issue of representation. The delegates did not seem to agree on the selection of representatives to the Congress.
The fundamental issue that was raised at the constitutional convention was slave trade and human rights abuses. Those were the issues that were strife then.
The taxes
control of commerce
The Constitutional Convention dealt with slavery issue in a conclusive manner. The addressed the rights of the slaves and their right to own property among other contentious issues.
slave trade
Choose members of Congress
representation of the states in congress
How the president should be elected.
The primary conflict of the Constitutional Convention was settling how states would be represented in Congress and whether this would be an equal number or vary based on population. The Connecticut Compromise resolved this issue.