A no-show is the worst outcome for everyone in the building. The room is staffed, the tickets are sold, and the reason it happened decides who pays for it.
What the contract says
Most European performance contracts treat a failure to perform as a breach. The artist returns any deposit, and the promoter can claim what has already been spent: venue hire, crew, marketing, ticket refunds. Some contracts add a penalty on top, and some cap liability at the fee.
When it is not a breach
Illness with a doctor's note, a cancelled flight, a closed border or a venue that loses its licence sit under force majeure or a specific illness clause. Those clauses release both sides without damages, but only where the wording covers what happened. Read that clause before signing, not on the day.
What to do instead
Tell the promoter the moment it is clear. A cancellation 48 hours out costs everyone less than an empty stage. Offer a replacement date, help find a replacement artist, and expect the fee to be gone either way.