Due to the financial success of the first film, Universal Pictures had long been interested in a sequel. The film was officially announced in May 2017, with Parker hired to write and direct. In June 2017, many of the original cast confirmed their involvement, with James being cast in the role of Young Donna that July. Filming took place from August to December 2017 in Croatia, and at Shepperton Studios in Surrey, England. A British and American joint venture, the film was co-produced by Playtone, Littlestar Productions and Legendary Entertainment.

Based on this passage, where was mama mia herewe go again filmed? Let's think fast. Stream of consciousness:
To answer this question, we should know that: Filming took place from August to December 2017 in Croatia, and at Shepperton Studios in Surrey, England. So the final answer is Croatia , and at Shepperton Studios in Surrey , England.