Fourteen years after his abrupt departure from the show, Conan O'Brien is returning to The Tonight Show, Deadline reported.

O'Brien was The Tonight Show host from June 2009 to January 2010. However, Jay Leno replaced him after his failed stint at the primetime slot.

This time, the former host is returning to his old stomping grounds as a guest. The Tonight Show is now hosted by Jimmy Fallon and O'Brien will be making an appearance on April 9.

He'll be on the show to promote his Max travelogue Conan O'Brien Must Go, which will premiere on April 18.

O'Brien made a brief appearance on the show in a short video skit with both Fallon and The Late Show's Stephen Colbert in 2018.

Conan O'Brien Must Go will see the host visit friends and fans he met on his podcast Conan O'Brien Needs a Fan, a spinoff of his other podcast Conan O'Brien Needs a Friend. The travel show will stop in Norway, Thailand, Argentina and Ireland.

The 2010 Tonight Show debacle

The issue with O'Brien and Leno was a watershed television moment. It was a huge media and public relations disaster that involved the two then-NBC late-night hosts.

Leno was The Tonight Show host since 1992, while O'Brien hosted Late Night since 1993. In 2001, O'Brien's contract was almost at an end and he was considering offers from other networks. NBC then offered to extend his contract as well as making him the next (and fifth) host of The Tonight Show.

However, NBC seemed to have forgotten to tell the show's current host, Leno, about this deal until 2004. Then they told him that O'Brien would replace him as host in five years. In 2009, the network tried to keep both hosts by giving Leno his own primetime show and O'Brien got the Tonight Show.

Both shows didn't have strong ratings at the start. The network's affiliates then complained about the falling viewership. NBC management then proposed a solution: Leno would return to the 11:35 PM ET slot while O'Brien would be moved to alter time at 12:05 AM ET.

This didn't make O'Brien and his staff happy as this wasn't the slot they were promised. The situation became heated when he didn't agree to the changes. The proposed changes caused a public outcry. There were even demonstrations supporting O'Brien.

He made a public statement and said that he wouldn't take part in destroying The Tonight Show. This led to his negotiation with NBC and a settlement. O'Brien and his staff received $45 million (adjusted for inflation, it's worth $65 million today) to leave the show. His final night hosting The Tonight Show aired on Jan. 22, 2010.

Leno returned to The Tonight Show in March and hosted until 2014, his retirement year. After a contracted seven-month television appearance ban, O'Brien went to TBS to host Conan.