I can't. Only when the statutory conditions or agreed terms come into effect, the contract is invalid. As long as the contract is legal and compliant, and the other party does not recognize my signature or considers it invalid, the contract will not be invalid. The parties may settle contract disputes through conciliation or mediation. If the parties are unwilling to settle or mediate, or the settlement or mediation fails, they may apply to an arbitration institution for arbitration according to the arbitration agreement.