Any sale made by mistake, or not in accordance with law, or obtained by fraud is void, and the purchase agreement or contract of purchase issued thereon is of no effect. In such case, the holder of the purchase agreement or contract shall be required to surrender it to the board of university and school lands, and the board, except in case of fraud on the part of the purchaser, shall cause the money to be refunded to the holder of the void purchase agreement or contract.