Why did the dred scott v. sandford decision anger northerners

Dred Scott v. Sanford (Sandford is a misspelling by the Court) decided essentially that black people could not be considered citizens—regardless of their residency, including in the North—and were therefore not entitled to sue in federal court. Further, the Dred Scott decision said that the federal government could not regulate slavery in its territories. So not only was this counter to the abolitionist sentiments of northerners, but it also struck down the Missouri Compromise, which was a potential, short-term compromise. But in addition to this decision being counter to abolitionism, it was plain racist and bad legal logic. It ignored Article III of the Constitution in favor of a convoluted and contradictory definition of citizenship. There's a reason this is often cited as the worst SCOTUS decision, ever.