From Law wiki, the wiki for law research

There are many ways in which the parties entering into a Contract can be mistaken about the contract. If the mistake is genuine then the contract will either be void (see: Void contract) or voidable (see: Voidable contract). The law recognises two classes of mistake:

• Agreement mistake, where the parties are acting at cross-purposes, and
• Common mistake, where the agreement is sound but it does not match the situation that obtains in the domain of the contract.