The festival, which always takes place on the summer solstice, started in France and has spread to many countries in Europe.
It provides a chance for amateur and professional musicians to play in bars, concert halls and on the streets.
But this year a few dozen bars and restaurants in Paris have opted to boycott the event in protest at measures to limit noise and disruption for residents by night-time revellers.
The boycott was launched by the Mayor of the Night, Clément Léon, who was elected by entertainment-oriented businesses.
About 40 venues, mainly in the east of Paris, were to close and around 30 others were to refuse to have music, live or otherwise, he said.