Art. 44 CISG
Notwithstanding the provisions of paragraph (1) of article 39 and paragraph (1) of article 43, the buyer may reduce the price in accordance with article 50 or claim damages, except for loss of profit, if he has a reasonable excuse for his failure to give the required notice.
The Secretariat Commentary does not adress Article 44 CISG, since there was no equivalent provision in the 1978 New York Draft, which formed the basis for the Secretariat Commentary.
Overview of case law on Art. 44 CISG: UNCITRAL Digest
The UNCITRAL Digest on the CISG can be used as a starting point to discover the relevant case law on this article.