(1) If circumstances that became the basis of a contract have undergone serious change since the contract was concluded and if the parties would not have concluded the contract or would have concluded it with different contents had they foreseen this change, then adaptation of the contract may be demanded to the extent that, taking account of all the circumstances of the specific case, in particular the contractual or statutory distribution of risk, one of the parties cannot reasonably be required to uphold the contract without alteration.
(2) It is equivalent to a change of circumstances if material conceptions that have become the basis of the contract are found to be incorrect.
(3) If adaptation of the contract is not possible or if one party cannot reasonably be required to accept it, then the disadvantaged party may rescind the contract. In the case of continuing obligations, the right to terminate takes the place of the right of rescission.