Final answer:
The new Fugitive Slave Law upset the North the most as part of the Compromise of 1850.
Step-by-step explanation:
The component of the Compromise of 1850 that most upset the North was the new Fugitive Slave Law. This law required Northern states to assist in the capture and return of escaped slaves, which was viewed by abolitionists and many Northerners as a violation of personal liberties and an endorsement of slavery. The North saw this component as a way to strengthen the power of slaveholders and perpetuate the institution of slavery.
Learn more about Compromise of 1850 and its impact on the North