Based on the error report in your social posts' reporting, you need to re-establish the API connection between your Constant Contact account and Facebook business page.
Social platforms, especially Facebook, will occasionally refresh their API permissions, which requires 3rd party connections to have to be re-established by the users. You can disconnect a social page from your Constant Contact account from the Social tab. You may also need to revoke our permissions on the Facebook side as well. Then you can reconnect the page and reinstate those permissions from the Social tab in your CTCT account.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ William A Community & Social Media Support