The costs have risen by 20% owing to unforeseen circumstances.
»The fund covers unforeseen expenses not paid for by insurance.
»unforeseen complications/difficulties/problems
непредвиденный, непредусмотренный
~ events {/lang] - непредвиденные события {последствия}
unforeseen events [consequences] - непредвиденные события [последствия]
непередбачений
- unforeseen circumstance- unforeseen event