A couple of mistakes that you might have made: 1. Letting the salt come in direct contact with the yeast or mixing the butter too soon - this would retard the yeast activity or using hot milk/water which would have killed the yeast in the first place and hence there won't be enough gas produced to make the rolls light. 2. Adding too much flour while kneading which causes the dough to dry making it harder. 3. Not kneading the dough enough thereby no gluten formed resulting in a dense and heavy crumb. 4. If your oven runs hotter than the specified temperature then the crust of the pav would get harder . Try to use an oven thermometer in that case. Follow the tips mentioned in the post to avoid all of this.