what is the pitra Dosha?
pitras are our own ancestors who have been thrown into pretha yonior any other lokas and asa result of this they become extremely restless and sad and expect to get mukti from that state through the karma of their successors they are considered to be more important to a person than any other devathaas(excluding sadguru) as they will be having blood relationship with their successors.
There are many rituals of pitra Dosha nivaran. Titr dosh is one of the biggest obstacle on the path to siddhi. Success is almost not possibleif one has pitra dosh in ones life.