@Lynn253 I've had the same error message when I try to block a date out that is outside my 6 month booking window. No problems if I'm blocking dates within the next 6 months (I only open my calendar 6 months in advance). It's only happening on my desktop, I've been able to block out dates on the app without a problem. Maybe use the app as a work around for the moment & raise a ticket with airbnb customer service to let them know there's a problem.
That sounds like it may be the issue though the beginning of what I block is within the window (3 months) the end is just out of it so perhaps that is causing the error! I'll try to block less and see what happens. Thanks very much!
@Lynn253 if you need to block outside of your availability window try the app. And you can raise a ticket by going into help when you're in your account, then click on the give feedback link. The more host who let airbnb know there is a big the more likely it will be looked at & fixed