Although the 2016 Rick Steves guidebook to Paris says that there is luggage storage at Versailles, that is not 100 percent accurate. My family and I arrived there toting overnight bags, believing we could store them while we toured, but we could not.
We were told that storage is quite limited so they only store bags containing food or drink, which they will not allow you to take in. Although I had a croissant and chocolates in my bag, the baggage check person said that it wasn't enough food to count for storage.
Plan to store you things elsewhere if you go!