The one-off show had been due to launch with the HBO Max streaming service in May, before Hollywood production was halted.
Last month Friends star David Schwimmer gave fans fresh hope and said filming could begin in August.
However, production has been delayed again and filming dates are yet to be determined, according to Variety. The PA news agency confirmed the news.
The Friends special will bring together Schwimmer and co-stars Jennifer Aniston, Courteney Cox, Lisa Kudrow, Matt LeBlanc and Matthew Perry.
It was announced in February and filming is set to take place on the show’s original soundstage, Stage 24, on the Warner Bros lot in Burbank, California.
Friends ran for 10 seasons from 1994 and remains one of the most popular shows on TV.