In the absence of a separate contractual agreement, the UN Convention on Contracts for the International Sale of Goods is applicable as part of the German legal system. Although this provides for liability for material defects regardless of fault, your Italian customer can in principle only demand cancellation of the contract if he has properly inspected the goods and given notice of defects, if the defect constitutes a fundamental breach of contract and if a reasonable period of time for rectification has expired to no avail. Furthermore, according to the UN Sales Convention, the amount of damages to be claimed is limited to the damage that was also foreseeable at the time of the conclusion of the contract: this excludes unforeseeably high compensation obligations. With regard to the duration of the warranty obligation, the limitation periods of German law apply, in this case two years.