The most likely explanation is that not enough vinegar was used, as this is the ingredient that preserves the chutney against spoilage. There needs to be at least 1 liter of vinegar to every 3 kg of fruit and vegetables. Other possible causes of mold are under-cooking the mixture, so it retains too much moisture, or the use of unsterilized jars.
Chutney with mold growing on its surface should not be eaten, as the mold may have produced toxins within the entire jar.
** Asian Recipes