This study is planned to test the safety and tolerability of the TIL regimen. The study will also test how well TIL fights cancer. The study will enroll children, teenagers, and young adults with solid tumors that have returned or are not responding to treatment for whom no effective standard-of-care treatment options exist. Study details include: * The study will last up to 2 years after the TIL infusion (Day 0) for each person. * The treatment will last up to 10 days for each person. * Study visits will be every 2 weeks until Day 42, every 6 weeks until Month 6, and every 3 months until Year 2.