Hac is not farz if debts prevent financial ability, but if you can maintain payments while affording Hac, many scholars permit it — seek creditor permission when possible.
The question of Hac with debts requires careful consideration of the Islamic principle of istita'ah (ability), which is a condition for Hac to become farz. The majority of scholars across all four madhahib agree that if a person has debts that prevent them from meeting their financial obligations, Hac is not yet farz for them — they should prioritize debt repayment. The rights of creditors are a serious matter in Islam.
However, the situation is more nuanced for people with long-term structured debts (mortgages, student loans, installment plans). If you can afford the Hac expenses while maintaining your regular payment schedule without defaulting, many contemporary scholars permit performing Hac. The Hanafi position tends to be more flexible on this, while the Hanbali position is stricter about clearing debts first. It is strongly sunnet to seek written permission from creditors and to make a written will before traveling in case anything happens. For voluntary (nafl) Hac — meaning you have already performed your farz Hac — scholars unanimously advise paying off debts first.
Source: Ibn Qudamah, al-Mughni; al-Nawawi, al-Majmu'; al-Kasani, Bada'i al-Sana'i