Context: A state's consent may be invalidated if there was an erroneous understanding of a fact or situation at the time of conclusion, which formed the "essential basis" of the state's consent. Consent will not be invalidated if the misunderstanding was due to the state's own conduct, or if the truth should have been evident.

Question: What on behalf of a state cannot invalidate that state's consent to a treaty?
Answer: own conduct

Question: Consent to a treaty will not be invalidated if what should have been evident?
Answer: the truth

Question: What may be invalidated if there was an erroneous understanding of a fact or situation at the time of conclusion of a treaty?
Answer: A state's consent

Question: An erroneous understanding of a fact or situation may only invalidate a state's consent to a treaty if what is also true about the erroneous understanding?
Answer: formed the "essential basis" of the state's consent

Question: What, if it formed the "essential basis" of a state's consent to a treaty, may invalidate that consent?
Answer: an erroneous understanding of a fact or situation