Opengraph plugin error

I'm not sure what's causing those PHP warning messages off-hand, but they aren't critical errors and likely shouldn't be causing any functional issues on your site. I've added this thread to our bug-tracker to investigate fixing for the next release.

Until then, what I'd recommend is going to the Joomla -> Global Configuration area and setting the "Error Reporting" option to "System" or "None", both of which should hide the non-critical PHP errors from appearing on your site.

Of course, if you're running into any issues with what the Open Graph plugin should be doing on your site, please let me know, and we'll gladly help however we can.

Thanks,
Alex