Normality of residual is violated, How to fix it properly? One of the key assumption of the OLS is that the normality of the residual.

If this assumption is violated, how can we fix it generally? 

Especially, I want to make predictions
Use Bayesian regression. It's much more flexible on its assumptions, and much more powerful in its outputs. You'll find that you have to be much more explicit about your assumptions, and you'll have to quantify them.

It's much harder work, and all the work you do, will be valuable.

Normal regression makes it very easy for anyone to do really bad science.

Bayesian regression makes it harder to do anything, but makes it much easier to do good science.