Buzz
In Dragon Ball, the Earth's dragon deity grants one wish to whoever gathers all 7 dragon balls. However, not every wish can be fulfilled.
There have been numerous wishes fulfilled by the dragon deity in Dragon Ball. However, not all wishes come to fruition; some wishes stump even the Earth's dragon deity.
Here are such wishes!
Reviving a Person Twice
This issue arose with Goku and his comrades when attempting to revive someone who had already been revived twice. The Z Fighters once sought to bring Krillin back after his second demise, but the dragon deity couldn't comply. Those previously resurrected by the dragon deity cannot be resurrected again. Put simply, each person can only be resurrected once by the divine dragon.
However, this restriction only applies to the Earth's dragon deity; the dragon deity on Namek isn't subject to this limitation.
Taking the life of a creature stronger than the creator of the dragon balls
The wishmaker cannot wish for something beyond the power of the creator of the dragon deity. For example, summoning the dragon deity and asking it to defeat a foe stronger than the one who created the dragon balls is an impossibility.
It has been confirmed in the manga that the dragon deity cannot take the life of a creature stronger than itself. Since the Saiyan Saga, many new adversaries have emerged known to be stronger than the dragon deity.
Granting multiple wishes
The Earth's dragon deity cannot fulfill multiple wishes for one person. Otherwise, the wishmaker would only need to wish for thousands of wishes to fulfill their desires.
Initially, users could make one wish, but later Dende revised it to two or three wishes, depending on the wish.
However, this might not be an issue for the super Shenron in Dragon Ball Super. As revealed, the super Shenron can fulfill anything. So, everyone wonders what would actually happen if the wish is: 'I want a million wishes.'
Reviving those who died from natural causes
Another wish that the Earth's dragon deity can't fulfill is reviving those who died from natural causes (old age, illness). For instance, Goku from the future passed away due to a heart disease, so Shenron can't revive him.
The dragon deity can only revive those who died from some kind of impact like being murdered or the planet being blown up.
Changing the time limit of the dragon balls
An immutable rule regarding those dragon balls is that after a wish is made, the dragon balls will revert back to stones, scattering in all eight directions and needing a year to restore into dragon balls.
That's the rule of the very orbs, so this issue can't be resolved by using wishes with the dragon deity.
