I get this error often. Still trying to find the reason.

I assume this is due to my poor and cheap hosting services.

This is not due to hosting. There is an error in the query's syntax.

md.name_id = 

There is nothing after the = to match to. @Burgs, are you able to search through the code for "WHERE NOT EXISTS". I don't think we use that anywhere in Elgg core so this query may be coming from a plugin. If you need this, there are instructions here for searching through code: http://docs.elgg.org/wiki/How_do_I_find_the_code_that_does_x%3F

heh, that's the query to search for lack of metadata.  How uncanny.

Note to self, make sure arguments exist! (I always do)

@Cash

Searched the full install, 2214 docs, but WHERE NOT EXISTS was not found. Even searched in lowercase but not found... using Dreamweaver.

@Burgs that codes has to be in there somewhere. Make sure the search is over php files. Dreamweaver may be set up to search over js and html files.

Try a search on just "NOT EXISTS". The "WHERE" part is generated programmatically.

Both

   .../engine/lib/access.php and

   .../mod/uservalidationbyemail/start.php

use some form of that phrase.

@willy good point - turns out it is a bug in the user validation by email plugin in the function

uservalidationbyemail_get_unvalidated_users_sql_where()

http://trac.elgg.org/ticket/4196

@willy... Thanks, good tip.

@Cash... If that bug is causing the error message, why is it still displaying after I disable the uservalidationbyemail plugin?  Also, why is a mirror install on another server and domain running OK and not displaying the error? Could the order of core plug-ins affect this?

Anyone?

If you disable the uservalidationbyemail plugin and still see this, you must have another plugin with a similar query. Try willy's suggestion of searching for "NOT EXISTS".