Untitled Night at the Museum Spin-off

Untitled 4th Night at the Museum film was a planned sequel to Night at the Museum: Secret of the Tomb.

Plot
Unknown

Why It Was Cancelled

 * 1) Night at the Museum: Secret of the Tomb was the last installment of the Night at the Museum franchise.
 * 2) Mickey Rooney and Robin Williams both passed away in 2014.

Results

 * 1) The film was permanently cancelled.
 * 2) The Night at the Museum film series ended up being a Trilogy.

Trivia

 * 1) Night at the Museum is getting rebooted for a Disney Plus series.