The first one happened during ADELE's tribute to GEORGE MICHAEL. She was singing his '90s hit "Fastlove", but it wasn't going too well, so she STOPPED. She said, quote, "I [effed] up, I can't do it again like last year . . . I can't mess this up for him."
Then there was the much-hyped METALLICA / LADY GAGA duet . . . which SHOULD HAVE rocked and it did, except for one thing: JAMES HETFIELD's microphone didn't work for the first few minutes.
He and Gaga were supposed to be trading verses, but his audio was non-existent. So it came off really bad until they fixed it. But the band & Gaga rocked thru it. Watch their performance here.
After it was over, James was so pissed, he threw his guitar offstage. For a lot of Metallica fans, it brought back the OUTRAGE of the '89 Grammys, when Metallica lost the inaugural Hard Rock / Heavy Metal Grammy to Jethro Tull.