WIKIPEDIA:

“ Warning is the sixth studio album by American punk rock band Green Day. It was released on October 3, 2000 through Reprise Records. Building upon its predecessor, Nimrod (1997), the album eschewed the band's trademark punk rock sound and incorporated acoustic and pop rock elements. Warning was also Green Day's first album since Kerplunk (1992) that was not produced by Rob Cavallo, although he did have a hand in its production and was credited as executive producer.
Despite mixed criticism towards the band's stylistic change, the album received mostly positive reviews from music critics. Although it peaked at number four on the ''Billboard'' 200 chart, Warning represented the lowest commercial slump in the band's career, being their first album since signing to a major record label not to achieve multi-platinum status. The album has nonetheless been certified gold by the Recording Industry Association of America, for shipments of 500,000 copies in the United States. Warning was reissued on vinyl on July 14, 2009.

Background
For Warning, Green Day initially opted to work with a producer other than Rob Cavallo, who had handled production of the band's last three albums. The group selected Scott Litt, who had previously worked with Nirvana and R.E.M.. [......] ”

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