MIX 104.1 announced the lineup for its annual MixFest concert. Headlining the stage at the DCR Memorial Hatch Shell on Sept. 17 will be OneRepublic (above), a band known for its hit songs “Apologize’’ and “Counting Stars,’’ singer-songwriter Ingrid Michaelson, and reggae pop star Shaggy (right). MIX 104.1 is still looking for a local singer to perform as the opening act at the free music festival. Apply at mix1041.cbslocal.com/open-mixfest. The deadline is Sept. 1.