After an hour of belting it out during his sixth LA date on the Saint Pablo tour, Kanye West gave up ...

The rapper's voice was giving out and he stopped singing, took a knee, and told fans the show couldn't go on. He said, "I'll do better next time."

The crowd booed and Kanye left the stage. Many concert-goers demanded a refund, though it's unclear whether Ticketmaster will offer any compensation. The set was only ten minutes shorter than planned -- for an extra concert date that was added only six days ago. Kanye's next stop is San Jose on Nov. 17, so he has a little time, now, to go home and relax and eat chicken soup with wife Kim K.

Speaking of Kim -- she was THERE! Kim went back to see her fourth LA show, with sis Khloe. But they stayed for only 45 minutes and then had their driver take them home. Weird!

Meanwhile, celebs like DJ Khaled and Usher seemed surprised by the shortened performance, heading out early from the Forum. New dad DJ Khaled left his baby boy and fiancee at home to fly out to LA to see the show ... guess he'll have to catch another show if he wants the full Saint Pablo experience!