To paraphrase the complaints made in a deposition and revealed in 2016, the showrunner felt the powers that be were being greedy and cheap to a degree that hurt the cast, crew, and creative integrity of the series. Darabont felt the execs, in response to his pushing back, concocted a reason to fire him by falsely claiming he was skipping tone meetings with the directors (via THR).
Perhaps most revealingly of all, we know that the cast supported their former creative captain. In 2022, Sarah Wayne Callies (Lori Grimes) called Darabont's firing an "assassination," saying that, in her words, "the reasons that we were given were that he's unexperienced as a showrunner and he's unprepared .. .But this motherf—er, one month before we started shooting Season 2, dropped six completed scripts in my lap [and] they were wonderful" (via The Wrap). Speaking to Entertainment Weekly, Melissa McBride (Carol Peletier) had words of high praise for Darabont, while Andrew Lincoln (Rick Grimes) looked back on the writer-director's firing with deep sorrow.
The lengthy lawsuit, with all its twists, turns, and tantrums, began as a plaintiff suing a defendant for money owed (and for engaging in shady practices in order to justify its withholding), evolved into a mudslinging fest, was eventually reigned back in to focus on the numbers, and finally came to rest in a settlement nearly a decade in the making. But at the heart of all this chaos lies a story every bit as old as the horror genre itself: the age-old battle between money and art.