Hey Arnold! The Jungle Movie (partially found cancelled original film adaptation of Nickelodeon animated series; 2002)
A fan's interpretation of what the original film's poster could have looked like.
Status: Partially Found
Hey Arnold!: The Jungle Movie is an animated feature film based on the Nickelodeon animated series Hey Arnold! that was to be released in 2002. Nickelodeon intended to release this film as the theatrical Hey Arnold! movie but decided to release Arnold Saves The Neighborhood instead. Nickelodeon was still interested in making the movie after the unsuccessful release of Arnold Saves The Neighborhood, but cancelled the project in 2004 after Craig Bartlet left Nickelodeon.
However, between November 23rd, 2015 and March 1st, 2016, it was announced that Nickelodeon would, indeed, be making the film as a TV movie with a 2017 release, even having Bartlet back as a writer as well as producer for the film.
The Original 2002 Film
While the film is confirmed to have been made, it's unknown if they will use any material from the original version. In the event, it's also unknown if Nickelodeon or Bartlet will release any of the original material somewhere or even how much of the film was made before cancellation.
However, there is a 40-second test clip of a scene involving Arnold's parents chasing a thief of some sort.