Does Hajj become invalid if the pilgrim commits a major sin after repenting and promising not to return to disobedience during the circumambulation (Tawaf)? And what should he do?

One who performed Hajj and committed a sin after making a covenant with Allah during the Tawaf must repent with sincere repentance, by abandoning the sin, resolving not to return to it, and feeling remorse. This sin does not affect the validity of the Hajj; his Hajj is valid. If he made a covenant with Allah using words that indicate commitment, then, according to some scholars, he must offer expiation for a broken oath (kaffarat yamin).