Every contractor has a responsibility to be vigilant when finalizing a contract. This responsibility is founded on the belief that each contractor is best placed to evaluate their own goals and interests, and is therefore best equipped to protect and advocate for them. The contract is a receptacle of conflicting interests and differing objectives for its parties, so each party should hold themselves accountable before blaming the other. In legal practice and doctrine, it has been established that a contracting party's error will not render the contract invalid or terminated if it is an inexcusable error resulting from negligence or a failure to investigate the truth. The study of inexcusable error aims to clarify its definition, its connection to the pre-contractual behavior of the parties, its evidence, benefits, limitations, prominent applications, and its role in achieving a balance between sound will and the principle of stability in transactions. The study finds that the concept of inexcusable error is not an afterthought to the theory of error, but rather a crucial condition for applying this theory. Maintaining the contract in the case of an inexcusable error is not a form of compensation, but rather an acknowledgment of the absence of a reason to nullify the contract, indicating the absence of legal error despite its existence in reality.