'Nobody Wanted' Anna Faris to Leave Mom, Source Says: 'It Was a Surprise'

Anna Faris' decision to leave the hit sitcom Mom after seven seasons came as a shock to those she worked with nearly every day.

"It was a surprise to hear that Anna was leaving," a source close to the show tells PEOPLE. "None of us are happy about that.

Faris announced her departure just days before the CBS comedy was set to resume production on season 8. (Due to the COVID-19 pandemic, the show's production schedule was pushed back and is now set to start on Sept. 14.)

"It was sudden and unwelcome, and it left the entire network scrambling," the source adds. "This is not a good thing at all."

The source says "no one" wanted Faris to leave — especially given the show's ongoing success.

"Mom has been one of CBS' more profitable scripted shows, in a very challenging economic time," the source explains. "And now one of the leads is gone. It’s actually a nightmare. No one wanted this."

A rep for Faris had no further comment.

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In a statement last week, Faris called working on Mom one of the most "fulfilling" and "rewarding" experiences of her career.

"The past seven years on Mom have been some of the most fulfilling and rewarding of my career. I’m so thankful to Chuck, the writers, and my amazing castmates for creating a truly wonderful work experience," Faris, 43, said in a statement. "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.”

Along with Faris, the Emmy-winning show also stars Allison Janney.

It is unclear how the Chuck Lorre comedy will write off Christy, Faris' character.