On April 2, 2015, the National released the single "Sunshine On My Back". The song is provided as a free download for renting or buying the band's documentary "Mistaken for Strangers" at its official website. The song comes from the "Trouble Will Find Me" recording sessions and features Sharon van Etten. The band headlined a handful of festivals during 2015, including Eaux Claires, a music festival held in Eau Claire, Wisconsin curated by Bon Iver frontman Justin Vernon and The National's Aaron Dessner. They also headlined Treasure Island Music Festival. In his review of the festival, "Consequence of Sound"s Zack Ruskin described the band's performance as "a masterclass in a band that has fully come into their own" and wrote that it "proved once again why they are one of the most exceptional and impressive rock bands of our time."