Prior to November 27, 1983 (the effective date of the 1983 Code of Canon Law) a future condition placed on a marriage only invalidated consent if the condition went unfulfilled. For example, Connie and Burt marry in 1970. Connie marries on the condition that Burt will soon inherit a substantial sum of money. If the money is inherited within the first few years of marriage, the marriage is valid. If he does not inherit the money, the marriage is invalid. However, a future condition placed on a marriage after the 1983 Code of Canon Law went into effect would immediately invalidate consent. If Connie married Burt in 1990 under the same condition mentioned above, then the marriage is invalid from the wedding day, regardless of any inheritance.
Michael S. Foster. Annulment, the Wedding That Was: How the Church Can Declare a Marriage Null (Kindle Locations 926-930). Kindle Edition.