For the last couple of weeks, I've been getting the following error in logs. I think it's happening when I save a post, as the frequency of the errors is about the same as the number of times I'm saving posts.
WordPress database error Query was empty for query made by do_action_ref_array, call_user_func_array, do_all_pings, do_trackbacks, trackback
Any idea what could be causing this? Here's a list of the sites that I'm pinging when posting if that helps: