Here's what they posted on their Facebook page.
⚠ Museum closed today ⚠
Due to a recent increase in visitor numbers, members of the Musée du Louvre’s Reception and Security staff are exercising their right to strike. The museum will therefore remain closed all day today (May 27, 2019).
We apologize for any inconvenience caused and thank you for your understanding.
To obtain refunds for tickets dated May 27, 2019, please write to: [email protected].
Visitor numbers are expected to remain high in the coming days. Only visitors with tickets purchased via the Louvre’s official website are guaranteed admission. For this reason, we strongly recommend booking online 👉 http://bit.ly/TicketingLouvre
📸 © Musée du Louvre / Maëlys Feunteun