According to The Hollywood Reporter, Lord and Miller had experienced creative differences with Lucasfilm producer Kathleen Kennedy, leading to their ultimate dismissal. It's unclear now who will replace them, but another hire is imminent as the film still has three weeks of re-shoots set to take place over the summer.
Lucasfilm released a statement about the directorial change on Tuesday, Kennedy referring to Lord and Miller as "talented filmmakers who have assembled an incredible cast and crew" while Lord and Miller cited "creative differences:"
"It’s become clear that we had different creative visions on this film, and we’ve decided to part ways. A new director will be announced soon," said Kathleen Kennedy, president of Lucasfilm.
"Unfortunately, our vision and process weren’t aligned with our partners on this project. We normally aren’t fans of the phrase ‘creative differences’ but for once this cliché is true. We are really proud of the amazing and world-class work of our cast and crew," stated Phil Lord and Christopher Miller.
The untitled Han Solo film remains scheduled for a May 2018 release."
THR claims one major issue was the directors' "clash" with screenwriter Lawrence Kasdan (Empire Strikes Back, Raiders of the Lost Ark).
Lord and Miller are best known for mega-sized comedies like The Lego Movie and 21 Jump Street.