Anna Faris’ ‘Mom’ Exit Was Reportedly a ‘Surprise’ That Has Producers ‘Scrambling’ for Path Forward

Anna Faris’ decision to leave the hit CBS sitcom Mom before production on the eighth season was not just a surprise to fans, but to her co-workers as well. The “sudden” decision reportedly has CBS scrambling for a solution moving forward and time is running short. New episodes are scheduled to begin filming on Monday, with Allison Janney returning as Faris’ on-screen mother.

A source close to the show’s production told PEOPLE Thursday Faris’ decision was a “surprise” and no one is “happy about that.” Her choice to leave was “sudden and unwelcome, and it left the entire network scrambling.” The source said it was “not a good thing at all” and “no one” wanted her to leave since the show has been a consistent hit ever since it began in September 2013.

“Mom has been one of CBS’ more profitable scripted shows, in a very challenging economic time,” the insider told the magazine. “And now one of the leads is gone. It’s actually a nightmare. No one wanted this.” Faris’ rep did not comment on the report.

Earlier this week, Faris made the stunning decision to leave Mom after seven seasons. Faris is leaving in the middle of a two-year contract signed before Season 7. “The past seven years on Mom have been some of the most fulfilling and rewarding of my career,” the actress said. “I’m so thankful to Chuck, the writers, and my amazing castmates for creating a truly wonderful work experience. While my journey as Christy has come to an end, allowing me to pursue new opportunities, I’ll be watching next season and rooting for my TV family.”

Faris’ Christy Plunkett will reportedly be written out of the show, leaving Janney to take the lead as Christy’s mother Bonnie. Janney has been the recipient of several awards for her performance on the show, including a Golden Globe nod in 2015 and back-to-back Emmy wins for Outstanding Supporting Actress in a Comedy in 2014 and 2015. The rest of the show’s lead cast includes Mimi Kennedy, Jamie Pressley, Beth Hall, and William Fitchner.

Mom was created by Eddie Grodetsky, Gemma Baker, and The Big Bang Theory‘s Chuck Lorre. The show centers on Christy and Bonnie, a dysfunctional duo living in Napa, California. Both are struggling to stay sober while attending Alcoholics Anonymous. According to TVLine, the show is CBS’ third-highest rated sitcom, behind Young Sheldon and The Neighborhood, which are also coming back later this year.