Can a contract be void from the start if both parties make a mistake in the construction of the contract?

A contract will be void from the start if a mistake by both parties renders the subject matter of the contract fundamentally different from what they believed to exist at the time they entered into the contract, so long as the party seeking to set the contract aside was not at fault for the mistake (Kessel v. Van Rikxoort, 2012 BCSC 1270, at para. 240).

In Dyson Estate v. Moser, 2003 BCSC 1720, the court at para. 20 adopted this statement: A contact (sic) will be void ab initio for common mistake if a mistake by both parties to the contract renders the subject matter of the contract essentially and radically different from that which both parties believe to exist at the time the contract was executed. However, the parties seeking to rely on the mistake must have had reasonable grounds for entertaining the belief on which the mistake was based. (emphasis added)