Sweet child o'mine is a song that impressed me the first time I heard it.
Initially, it was due to Axel and Slash interpretation, later, it was the whole thing as well as the Appetite for Destruction album.

At some moment on my life, I played the rythm guitar on an amateur band and we performed that song from time to time. Not so good, but well, me and friends were having fun.

One point of debate inside the band, was the fourth chord in the main solo. 
For me, it was an A major because "with minor it sounds like an arabesque song!".
For the 1st guitarrist, it was a minor: "it sounds just bad with major!".

The most musically studied guy in our band, was the bassist. According to his theory, it has to be a minor. 
His theory was more or less on the same line of the following analysis:
https://www.guitarmusictheory.com/sweet-child-o-mine-guitar-solos/

Lot of basic tutorials also consider this chord to be a minor (Justin Guitar to mention one)

I have seen a lot of partitures for this song. Some captures of the discussed part also show that I was wrong:

[![Start of main solo][1]][1]

So, according to "some" theory, it should be a minor, even if my ear says otherwise.

Some days ago, some of us reunited and decided to play that song... and the debate emerged again!

Well, I was trying to understand what is happening here. How my ear can lie that bad. After all, it is a power chord for most of the time. Why my ear is filling it with the major third?
I have also analyse some of the solo fragments of that beat in partitures. It mostly avoids the 3rd interval, but it plays the minor in very quick parts (may be a transcript error?). 
It is also nociceable that the chorus is A major without any doubt, same for the second half of the main solo.

Then, I was looking for videos that capture the exact chord inversion with image and sound with not much luck.
But I captured this frame of Guns and Roses in the exact moment:

[![chord][2]][2]

It is not very clear to me. But I'd say it is the open D chord transposed to the 7th freet. So, an A major.

Then I found this very basic tutorial. This guy is not using advanced chords, but he is agreeing with me:
https://www.youtube.com/watch?v=4wNECaVVv_E (around 15:02, he plays the A major for that part)

Have anyone had same doubts as me for this song?
What is the theory, if any, that could explain that the rythm plays major third but the solo uses the minor?
Does anybody has a strong argument for the A major or minor chord?

Help the band to stay reunited!! :D

  [1]: https://i.sstatic.net/aGx3H.png
  [2]: https://i.sstatic.net/4RrxT.png