I've been using org 9.0.7/GNU Emacs 25.1.1 on Mac OS X for a while, and successfully exporting HTML to copy and paste into my blog.
However, in the last day or so, this started failing. I'm unaware of having changed anything in my configuration.
The error is ...
Here's the entire file I'm using ...
+============
Does this work at all?
+============
Here's the debug traceback ...
+============
Debugger entered--Lisp error: (wrong-type-argument listp #("org test" 0 8 (:parent (#1))))
Kaushal Modi