There are two Harry Potter questions JK Rowling NEVER wants you to ask again
She-Who-Must-Be-Asked has two unforgivable questions

As the woman with the keys to the magical kingdom that is the Harry Potter universe, JK Rowling’s often asked more questions than any muggle could handle.
And she replies to as many of them as possible with grace and humour, because she’s lovely and creative and really appreciates fans of the novels. Just look at the 21 burning Harry Potter questions she answered AFTER the books were published for a shining example.
But the author has her limits, and deems some questions just too much to handle. You might say they’re the “unforgivable questions” that the author just can’t be dealing with – like ‘is the Cursed Child a prequel?’
@jk_rowling You should really put #NotAPrequel in your Twitter-bio to avoid answering the same questions eleventy billion times.
— Dan F. (@avatar81) February 11, 2016
Or this. Never, ever ask her this.
Along with "the Horcrux wasn't destroyed in CoS because Harry didn't die #PleaseNeverAskMeThatAgainPlease" https://t.co/ih4QwuQncI
— J.K. Rowling (@jk_rowling) February 11, 2016
Oh, and in case you missed it, The Cursed Child book isn’t a novel.
And The Cursed Child play isn’t a prequel.