Guns N' Roses have delighted life-long fans with their upcoming reunion after Slash and Axl Rose apparently settled their differences.

But what was behind the guitarist and frontman's bitter bust-up in the first place?

According to Tom Zutaut, who signed the legendary band, the feud began when Slash overdosed on heroin and "died" for eight minutes.

Axl, 53, thought a different Slash took over his body following the overdose.

“Axl genuinely believes the soul of Saul Hudson left his body when Slash OD’d," Tom said on The Most Dangerous Band in The World documentary.

(Image: WireImage)

"That is the greatest stumbling block to getting the band back together.”

Whatever the reason, the duo managed to put their differences aside to headline Coachella in April.

It will be the first time the classic line-up of the group will have been together on stage since 1993.

(Image: REX/Shutterstock)

Read more:What do Guns N' Roses look like now? Slash, Axl Rose and the gang are getting back together

Meanwhile, former bassist Tommy Stinson has said the reunion will be a "healing process".

In an interview with American radio station The Current, he said: "I think everyone kind of knows where I stand with it all. I left it in a good way. I mean, roughly, I actually had to just start turning down tours because I was unable to tour; I got into a position, personally, where my personal life was going to prevent me from doing it.

"I don't know, it must have been about five tours that they called me to do, and I just said I can't do 'em. And at that point, they... I think Axl got to the position where he was, like, 'OK, so what am I going to do now? 'Cause I don't have a band. Blah blah blah.' So I think it worked out.

"I think they'll have fun. It will be a healing thing for them, if it works out good. It will be good for them."