Thanks @elliefairholm ! Yes, my devel box was too old to support 26 (a problem with openssl IIRC) so I dropped to 24. But it gave me the motivation to get this box upgraded. 
I will retry and I’m sure that will fix it.
I totally support that philosophy of the reader using exactly the same versions that you did when you wrote the book. So this one’s on me for sure.
And thank you for this book! I know a little bit about some of these technologies, but I am really deepening my knowledge and filling in some holes… learning a lot. Well done.
All the best!