This is a tricky problem that is very misleading as the Jetpack error shown does explain the problem, but doesn’t explain that the actual problem may be hidden.
I believe the problem is dependent on your server error display settings, outside of WordPress’s control, which is why I only found about a dozen people just as stumped as I was.
The following Jetpack error occurs while trying to connect your blog to wordpress.com:
Your Jetpack has a glitch.
Something went wrong that’s never supposed to happen.
Guess you’re just lucky: xml_rpc-32700
Try connecting again.
Error Details: The Jetpack server could not communicate
with your sites XML-RPC URL. Please check to make sure
domain.com/xmlrpc.php is working properly.
It should show “XML‑RPC server accepts POST requests only.”
on a line by itself when viewed in a browser and should
not have any blank links or extra output anywhere.
If you visit
domain.com/xmlrpc.php, you’re immediately scratching your head – as just like me, you do see the expected
XML‑RPC server accepts POST requests only. With no white space or php errors.
So what’s the issue then?
WordPress turns off errors on
XMLRPCREQUEST via line
/wp-includes/load.php meaning what Jetpack is trying to show you, will not show because of WordPress (or your server settings may also be responsible: you may have a
display_errors 0 error settings that are out of reach WordPress/Jetpack debug efforts).
To, to solve this issue, in short:
Make sure your WordPress install/admin has NO ERRORS. None, whatsoever.
My errors were a result of the Domain Mapping plugin – it’s a few years old and had some depreciated functions. I turned on
wp-config.php, visited my WordPress Dashboard, saw the errors and fixed them. These errors would not show in
domain.com/xmlrpc.php, but they did show in my blogs WordPress Dashboard.