Sometimes people trying to buy a book on Leanpub see this message:

{"message":"Couldn't complete the cart purchase right now. Please try again later."} 

We believe that sometimes people get this error when they experience an intermittent issue with internet connectivity, and sometimes purchasing works properly if they try again later.

If you don't want to wait, checking out to make your purchase with the PayPal option, rather than our credit card form, sometimes works even if there is an error with the credit card form. You can also try making the purchase using a different internet browser.