Hmm,

forget that, it seems ther was something returned but crappy. restting 
each users personal setting seems to solve the issue.

Was something important changed in the serializer/pref-storage 
routines in the last month?

Hi,
are you using tasks while syncing? I re-saved the prefs, it doesn't 
help so I investigated the error a bit:


the mentioned error message is caused in horde/nag/lib/Nag.php in line 1603.

this line is located in the function "static public function getSyncLists()"
The first line festes the prefs an serializes the value:
         $cs = unserialize($GLOBALS['prefs']->getValue('sync_lists'));

The returned array contains usually some content:
Array
(
     [0] => or6rhw_UzWWoM8q5BrkCVA1
)

But sometimes it does not:
  Array
(
     [0] =>
)

As far as I know, the latter is not an empty array according to PHP 
definition, so the following  "if (!empty($cs)) "fails.

The above array is created by the function unserialize.
A debug revealed that "$GLOBALS['prefs']->getValue('sync_lists')" does 
not reveal always a value. So unserialize (btw: in which file is that 
unserialize function located?) should be fixed to return a proper 
emtpy value if the input is NULL.

Thanks,
Torben

I don't see this. I am successfully syncing calendar/contacts/tasks/email.

What is the value being passed to array_flip()? You can try re-saving 
Nag's synchronization prefs via the UI, perhaps it got corrupted 
somehow?

Horde throws a lot of PHP errors:

HORDE: [nag] PHP ERROR: array_flip() [<a 
href='function.array-flip'>function.array-flip</a>]: Can only flip 
STRING and INTEGER values! [pid 8825 on line 1603 of 
"/usr/share/php/www/horde/nag/lib/Nag.php"]

This seems also to break calender syncronization via ActiveSync at all!