Unforeseeable issues sometimes arise just prior to closing the sale. With negotiation, most of these issues have a workable solution but it’s not always the case. At this point, try negotiating calmly with the buyer and look at all possibilities. What could have been a “deal breaker” can be turned into a win-win situation for both parties.
In some cases, both parties might agree that the deal be called off. The seller can always find another buyer and the buyer can always find another home. To protect yourself against last minute “buyer’s remorse”, make sure the contract closes as many loopholes as possible after all known defects have been fully disclosed.