public void ModelState_AddErrorMessageFromException_ShouldRenderCorrectMessage_InFrench() { Thread.CurrentThread.CurrentUICulture = new CultureInfo("fr"); var modelState = new ModelStateDictionary(); var exception = new Exception("An error occurred while updating the entries. See the inner exception for details. Cannot insert duplicate key row in object 'dbo.Country' with unique index 'IX_TwoLetterCountryCode'. The statement has been terminated."); modelState.AddErrorMessageFromException(exception, new Country { TwoLetterCountryCode = "SDF" }); Assert.Equal("Un pays avec le Code Pays à Deux Lettres 'SDF' existe déjà.", modelState["TwoLetterCountryCode"].Errors.FirstOrDefault()?.ErrorMessage); }