EXCLUSIVE: HBO has stopped production on its high-profile six-hour miniseries Lewis And Clark starring Casey Affleck and Matthias Schoenaerts and executive produced by Tom Hanks and Brad Pitt. We hear there were internal as well as external, weather-related factors that have impacted the production, leading to what has been described as a rough shoot so far. As a result, HBO is taking some time and will be making two major behind-the-scenes changes.

“We are temporarily pausing production on the HBO miniseries Lewis And Clark,” HBO said in a statement to Deadline. “For creative reasons, director John Curran and director of photography Rob Hardy will be leaving the production. We will be bringing on a new director, and we plan to resume filming as soon as possible.”

There is no date set yet for when filming will resume.

Based on the book Undaunted Courage by Stephen E. Ambrose, Lewis And Clark tells the story of America’s first contact with the land and native tribes of the country west of the Mississippi River. The miniseries follows the epic journey of the Corps of Discovery and its captains, Meriwether Lewis (Affleck) and William Clark (Schoenaerts), who traverse uncharted territory on a mission to deliver President Jefferson’s message of sovereignty as they search for his fabled all-water route to the Pacific.

Lewis and Clark is listed as HBO and National Geographic Studios present a Playtone, Plan B and Class 5 production; Michelle Ashford, Curran and Edward Norton are the writers. Executive producing are Hanks, Gary Goetzman, Norton, Pitt, Dede Gardner, Tim Kelly and Adam Leipzig.

HBO recently paused production on another project, David Fincher’s 1980s music video industry comedy series referred to as Videosynchrazy.