Economists agree that increases in the money-supply growth rate increase inflation and that inflation is undesirable. So why have there been hyperinflations and how have they been ended?

Typically, the government in countries that had hyperinflation started with high spending, inadequate tax revenue, and limited ability to borrow. Therefore, they turned to the printing presses to pay their bills. Massive and continued increases in the quantity of money led to hyperinflation, which ended when the governments instituted fiscal reforms eliminating the need for the inflation tax and subsequently slowed money supply growth.