OCTAVIA SPENCER doesn’t think there’s any mystery why NBC pulled the plug on a “Murder, She Wrote” reboot – a source says she blames the original show’s star Angela Lansbury!

As The ENQUIRER previously reported, Lansbury, 88, was said to be against the reboot and lobbied the network to dump the idea – and that didn’t sit well with Octavia, who was slat­ed to star in the new “Murder, She Wrote.”

“Octavia thinks An­gela sabotaged the whole project by throwing her weight around,” revealed an insider.

Lansbury starred as mystery writer and amateur detective Jessica Fletcher in 264 episodes of the popular show, from 1984 to 1996 – and Octa­via, who won an Oscar for her role as a sassy maid in the 2011 film “The Help,” was hoping to step into her shoes.

But now, the insider says Octavia, 43, believes that Angela didn’t think she was talented enough to carry the lead role, adding: “It’s turned into a bitter feud.”

After the network decided not to launch the new version, An­gela publicly blasted the project as “an awful mistake” but praised Octavia as “a su­perb actress.”

“She had no business being put into a situ­ation that she couldn’t win,” noted Angela. But the insider said: “The fact is, Angela was against the whole idea unless they were going to bring her back.”

Even though Angela apparently got her way, she’s now said to be upset at Octavia for pointing a finger of blame at her.

“She thinks it’s rude and insulting,” said the source. “I guess the message here is, Don’t mess with ‘Dame’ An­gela Lansbury!”