Different countries have different rules on what constitutes a "breach" of contract and what the consequences are. Under Chinese law, for instance, there is the concept of 根本违约 ("fundamental breach") - where the breach is such that the purpose of the contract becomes impossible to be achieved - which gives the innocent party the right to terminate the contract and seek compensation. Therefore, the term here 严重违约 "material breach" is used loosely; contract laws of the country in question should be consulted in more detail.
a violation serious enough to change the nature of the agreement and give the non-breaching party the right to withdraw from the contract and/or bring an action for damages
If there is a material breach by either party there should be a right for the injured party to terminate the contract.