The increasing development of international trade requires the existence of transparent and universal rules to regulate commercial relations and determine the guarantees of performance arising from the breach of contract. The Convention on the International Sale of Goods (Vienna 1980), as one of the most important international documents, has provided a coherent legal system to explain the obligations of the parties and the responsibilities arising from the breach. The main issue of the present study is the complexities in identifying and distinguishing the types of breach of obligation and how to apply specific and joint guarantees of performance for the seller and the buyer within the framework of this international document. In many contracts, ambiguity in the scope of the concept of fundamental breach and how to apply compensatory rights can lead to long disputes in international sales. Accordingly, the purpose of the present study is to legally examine the liability of the seller and the buyer in the evef ordinary and non-fund performance in the event of foreseeable breach, the need for the injured party to mitigate damages, and the possibility of exemption from liability due to force majeure (Article 79). Overall, the Convention's approach to determining the liability of the seller and the buyer is based on good faith, preserving the contract as far as possible, and fair compensation for loss.