Netflix’s live-action Avatar: The Last Airbender series has apparently hit a major snag: On Wednesday original series co-creators Michael Dante DiMartino and Bryan Konietzo announced they have quit the project after two years of development.

DiMartino revealed on his website that he and Konietzko exited the production in June.

“When Bryan and I signed on to the project in 2018, we were hired as executive producers and showrunners,” he wrote, as first reported by Slashfilm. “In a joint announcement for the series, Netflix said that it was committed to honoring our vision for this retelling and to supporting us on creating the series. And we expressed how excited we were for the opportunity to be at the helm. Unfortunately, things did not go as we had hoped.”

DiMartino noted that throughout his career, he’s come to know that productions can bring with them unexpected complications. Normally, he said, he’s tried “to be like an Air Nomad and adapt... But even an Air Nomad knows when it’s time to cut their losses and move on.”

“I realized I couldn’t control the creative direction of the series, but I could control how I responded,” DiMartino added. “So, I chose to leave the project. It was the hardest professional decision I’ve ever had to make, and certainly not one that I took lightly, but it was necessary for my happiness and creative integrity.”

Director M. Night Shyamalan’s live-action Avatar film, The Last Airbender, was widely derided upon its release in 2010. Its notorious flop can be blamed on a number of failings—including its whitewashed casting, overly serious tone, and unimpressive action sequences, to name a few.

Because of that disaster, many Avatar fans are understandably skeptical of another live-action interpretation. DiMartino and Konietzko’s involvement in the Netflix series was the backbone of its credibility. Without their input, it’s difficult to know how fans will react to the new production.

Konietzko posted his own statement about the departure on Instagram, writing, “Big sigh.”

“This is probably the most difficult decision I have ever made,” Konietzko wrote in a statement. “But there is no doubt in my mind it was absolutely the right choice.”

“When Netflix brought me on board to run this series alongside Mike two years ago, they made a very public promise to support our vision,” Konietzko continued. “Unfortunately, there was no follow-through on that promise.”

Although he granted that he’d worked with “some great individuals” on the production, Konietzko characterized the production more broadly as “a negative and unsupportive environment.”

“To be clear,” he added, “this was not a simple matter of us not getting our way. Mike and I are collaborative people; we did not need all of the ideas to come from us. As long as we felt those ideas were in line with the spirit and integrity of Avatar, we would have happily embraced them. However, we ultimately came to the belief that we would not be able to meaningfully guide the direction of the series.”

A source confirmed to The Daily Beast that the series will move forward without DiMartino and Konietzko.

Both Konietzko and DiMartino conceded that whatever version of the story Netflix eventually releases could still be successful. “But,” DiMartino wrote, “what I can be certain about is that whatever version ends up on-screen, it will not be what Bryan and I had envisioned or intended to make.”

DiMartino and Konietzko’s departure is also bewildering because one would think, given Avatar: The Last Airbender’s incredible performance upon its Netflix release—and the upcoming, much touted Legend of Korra debut to follow this month—Netflix would be invested in keeping the show’s original creators on board. Nonetheless, the two parties apparently could not make the collaboration work.

DiMartino said that he is not finished telling stories in the Avatar universe. Nonetheless, he added, “Writing this letter has left me with a very heavy heart. I know many of you will be disappointed and frustrated by this news. I get it. I share your disappointment and frustration. I also recognize this creative setback is small compared to the problems we’re all facing as a society right now.”

“Thankfully, Iroh offered some wisdom for that, too,” DiMartino concluded. “‘Sometimes life is like this dark tunnel. You can’t always see the light at the end of the tunnel, but if you just keep moving you will come to a better place.’ May we all keep moving and come to a better place.”

A representative for Netflix told The Daily Beast, “We have complete respect and admiration for Michael and Bryan and the story that they created in the Avatar animated series. Although they have chosen to depart the live action project, we are confident in the creative team and their adaptation.”