why did war of succession broke out after the deadth of mughal emperor
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Answers
The descendants of Timur (including the Mughals) had no clear succession policy. The eldest son didn't always get the whole kingdom; he usually had to fight a bit. Babur only invaded India in the first place because his cousin threw him out of Samarkand. And the infighting didn't start after Akbar - even Humayun had to fight a long civil war with all his brothers (despite being both the eldest AND Babur's appointed heir).
Akbar didn't have to fight anyone because he didn't have any important siblings. He did have to exile Bairam Khan and kill his foster brother (Adham Khan, I think).
Jahangir did not have to kill his brothers because they were pretty hopeless (one of them accidentally poisoned himself by drinking alcohol out of the barrel of a gun).
Unfortunately, Jahangir's most useless son had Nur Jahan for a mother-in-law. Nur Jahan really wanted to be mother of a queen after Jahangir died. Khurram (the least useless son, who would later change his name to Shah Jahan) really wanted to be king. Jahangir listened to Nur Jahan's advice, but Khurram was older - so there had to be a war. (I'm not too sure about what happened to the eldest, Khusrau. I think he turned against Jahangir and lost.)
With Shah Jahan's sons, the conflict was a bit more complicated. Shah Jahan didn't want a civil war, so he pushed his younger sons away to govern distant provinces, and kept the eldest (Dara) at home. So Dara ended up with no experience of conquering, but with an idea that he was destined to rule; Aurangzeb had conquered the Deccan and was a very sneaky politician. The other brothers took advantage of the chaos.
When Aurangzeb died, there were about 17 sons, grandsons and great-grandsons, most of whom mistrusted each other because Aurangzeb liked imprisoning children who disagreed with him. There were no decent rulers afterwards, so the internal unrest just got more complicated.
In short, the succession wars were mostly a result of the Timurid succession policy, but also partly because each generation (barring Akbar's) produced multiple people who thought they could and should be king. I don't know about the Rajputs, but most Indian rulers followed the primogeniture system (i.e eldest son gets everything), not the Timurid system.
Edit: Akbar did have a brother. The nobles who disliked Akbar crowned this brother as a parallel emperor at some point in the 1570s-1580s. Akbar was able to bring the situation under control very fast and with minimum mess, and so our history books don't make a big deal out of it as they do for the protracted civil wars flight by other Mughals.
The war of succession which took place among the four sons of Shah Jahan had one novelty. While previously, wars were fought after the death of the emperor, this war was fought when Shah Jahan was yet alive. Besides, all sons and daughters of Shah Jahan participated in it. While the four sons Dara Shikoh, Shah Shuja, Aurangzeb and Murad Bux fought against each other, the sisters allied themselves with one or the other brother. Jahan Ara supported Dara Shikoh, Roshen Ara supported Aurangzeb and Gauhan Ara sided with Murad Bux. Likewise the nobles and army commanders sided with one or the other contestant of the throne.