Hm, it seems like this will be the similar issue from what you facing on Easysocial. https://stackideas.com/forums/previous-fix-not-working-on-update-to-es-3-1-4#reply-467410

I did added this code from this file on your site JoomlaFolder/administrator/components/com_easydiscuss/includes/easydiscuss.php :

		if (!$saGroup) {

			$obj = new stdClass();

			$obj->id = 8;

			

			$saGroup[] = $obj;

		}

It should work fine now.

By the way, if you do not want to notify those email notification to your site admin then you can disable these setting https://take.ms/Xd1mp so it will not trying to find your site admin account.

I thought I had added that modified code after updating... but maybe not.

Thank you very much

Oh actually that thread what I mentioned to is under Easysocial.

What I modify that file is under Easydiscuss component, is it you needed to send notification to your site admin when someone publish a new discussion or reply on your site?