Based on Judgment of the RF Supreme Court Chamber on Economic Disputes No. 309-ЭС15-3840, 14 September 2015The article is devoted to two major issues: limits of the enforceability of settlement agreement, and invalidity of settlement agreement concluded under the influence of party’s error in substantial fact. First, based on the commented judgment and historical statutory review, the article proves that the view that a court settlement agreement should be enforceable without further judgments is wrong. Such enforceability does not necessarily follow from the nature of the settlement agreement. Given this, the requirements to such agreements should be relaxed to include, for example, «frame clauses». Second, the article analyzes existing approaches of developed jurisdictions to the issue of challenging settlements concluded under the influence of error in factual background. It is suggested that legal significance should be attached only to the facts that had been considered by the court at trial hearing.