@German As per the policy of RBI no bank can offer debit cards to minors; therefore technically no bank can offer UPI for IPO of minors in India as of today. For them, it's only ASBA (online or paper).
@Anshujii Yes bank software automatically disabled my minor account. I approached their local team (branch), and customer care (Bombay) but those ignorant, ill-informed staff couldn’t provide the solution. Instead of spending my valuable energy to crack those hard nuts, I switched the bank.
@PavanM Now I am using RBL online ASBA (After the suggestion of a gentleman in Chittorgarh) for applying on my son's name. German you can try to update the minor PAN in his account and if the YBL software reflects the option for a minor then no need to change the bank as suggested by Anshuji. Hope I am clear.