Mistake must be that of (a) the object of the contract, or to (b) those conditions which have principally moved one or both parties to enter into the contract
Mistake as to the identity or qualifications of one of the parties will vitiate consent only when such identity or qualifications have been the principal cause of the contract
Mistake or error as to motive does not vitiate consent
A simple mistake of account shall give rise to its correction
There is no mistake if the party alleging it knew the doubt, contingency or risk affecting the object of the contract
Mutual error as to the legal effect of an agreement when the real purpose of the parties is frustrated, may vitiate consent
Violence - when in order to wrest consent, serious or irresistible force is employed
Intimidation - when one of the contracting parties is compelled by a reasonable and well-grounded fear of an imminent and grave evil upon his person or property, or upon the person or property of his spouse, descendants or ascendants, to give his consent
Undue Influence - when a person takes improper advantage of his power over the will of another, depriving the latter of a reasonable freedom of choice
Fraud - when, through insidious words or machinations of one of the contracting parties, the other is induced to enter into a contract which, without them, he would not have agreed to