J.J. Abrams has officially joined Twitter.

With his first tweet, the “Star Wars IX” director announced the start of production on the film, but noted the “bittersweet” feeling of going ahead without Carrie Fisher.

RELATED: Cast Revealed For ‘Star Wars’ Episode IX, Carrie Fisher To Return As Princess Leia Via Unseen Footage Shot For ‘The Force Awakens’

Abrams also thanks the cast and crew, “The Last Jedi” director Rian Johnson and “Star Wars” creator George Lucas for paving the way for the upcoming sequel.

Last week it was announced that Carrie Fisher will appear in the final film of the Skywalker saga using unseen footage from Abrams’ previous entry in the franchise, “The Force Awakens”.

RELATED: Carrie Fisher’s Brother Todd Fisher Reacts To ‘Star Wars: Episode IX’ News: ‘This Is Going To Be Very Magical’

Also appearing in the film will be Mark Hamill and Billy Dee Williams, as well as newer stars of the “Star Wars” universe Daisy Ridley, Adam Driver, John Boyega, Oscar Isaac, Lupita Nyong’o, Domhnall Gleeson, Kelly Marie Tran, Joonas Suotamo and Fisher’s daughter, Bille Lourd.

“Star Wars IX” is set to open December 20, 2019.