Surely, the situation and the appropriate ruling has been hashed out previously on BW, but I can't locate the threads.
South opens 1NT.
West bids 2H (alerted and explained as showing hearts and a minor).
Defense is off-track and inadequate.
Turns out that West held a one-suited hand, hearts only.
The convention cards of both East and West showed Hearts and a Minor.
Declarer was silent throughout. Was he required to advise, prior to the lead, that the explanation was incorrect?
Plus... it's free!