IComparer (ou os métodos IComparable nos quais se baseia) não devolveu zero quando Array.Sort chamou x. CompareTo(x). x: 'X' Tipo de x: 'Type Name' The IComparer: 'Y'.

Unable to sort because the IComparer.Compare() method returns inconsistent results. Either a value does not compare equal to itself, or one value repeatedly compared to another value yields different results. x: 'X', x's type: 'Type Name', IComparer: 'Y'.