There does not appear to be a stated reason from Nickelodeon of 'WHY' it was cancelled. Nickelodeon apparently aired the final episode and didn't announce they were the final episodes. If the internet can be believed Nickelodeon fired Craig Bartlett when he began making a show for Cartoon Network, however it was announced In July 2017, there would be a follow up two hour movie to the series, titled Hey Arnold Jungle Movie set to air sometime in November 2017. It will answer the unanswered questions and reveal the whereabouts of Arnold's missing parents. Exact airdate yet unknown.
There are 5 seasons of Hey Arnold.
Hey Arnold! debuted on Nickelodeon in October 1996 & aired until June 2004.
Gerald.
In 2006 in an online chat with Hey Arnold! fans, Bartlett revealed that Arnold's grandpa used his last name throughout the series, almost confirming that Arnold's last name is "Shortman".
Shortman.
2003
Disagreements with the creator and Nickelodeon resulted in the series being cancelled.
Hey Arnold! was created by Craig Bartlett .
There are 5 seasons of Hey Arnold.
"Watch hey Arnold" is not a question therefore cannot be answered at this time.
Hey Arnold - 1996 Arnold's Thanksgiving 3-14 was released on: USA: 18 November 1998
Hey Arnold - 1996 Arnold's Valentine 1-20 was released on: USA: 14 February 1997
Hey Arnold - 1996 Arnold's Christmas 1-19 was released on: USA: 14 December 1996
Hey Arnold! debuted on Nickelodeon in October 1996 & aired until June 2004.
No.
Gerald.
In 2006 in an online chat with Hey Arnold! fans, Bartlett revealed that Arnold's grandpa used his last name throughout the series, almost confirming that Arnold's last name is "Shortman".