Is the Hajj of one who is in debt invalid? And what should he do for his Hajj to be accepted by Allah?

The Hajj is valid for someone who owes a debt, but he incurs sin because repaying the debt is obligatory, whereas Hajj is not obligatory for him in this situation due to the absence of the condition of ability (istita'ah). The debt is tied to his responsibility and does not invalidate the performance of Hajj, and no scholar has issued a fatwa stating the invalidity of the Hajj of someone who owes a debt.