Harry Styles Debuts New Album 'Fine Line' At The Forum

Harry Styles packed The Forum in Inglewood, CA Friday night ... and the resale prices were INSANE!!!

Harry debuted his new album, "Fine Line" but didn't stop there. He rejiggered the One Direction hit, "What Makes You Beautiful" into a rock version.

And then ... Stevie Nicks walks out onstage and she and Harry did a duet of "Landslide" ... which was awesome. Harry also got in the xmas spirit, singing, "Wonderful Christmastime."  As he sang, confetti fell from the rafters. Hey, it's as close to snow as Los Angeles is gonna get, right?

As for ticket prices ... get this. All seats went on sale originally for $25. The Forum sold out in seconds. And then, the resale. $400 for nose-bleed seats. $1600 for floor seats!!! And people were paying.

Harry seemed extremely grateful for it all, telling the crowd how lucky he felt to unveil his album this way.