Hi!
I have the same error messages. I could identify the plugins “Publish” and “Share” from Jetpack package to cause this.
However, the error only occurs on pages and posts that are created before Jetpack was installed (and the above plugins activated).
Is there a fix around, i.e. database entries to the older pages/posts?
I am using WP 3.9.1 and Jetpack 3.0.1
Thanks!
gammascorpii.