[horde] ActiveSync: Device not found

[Thomas Bühlmann]

Hello List!

Since few days i'm facing a strange problem:
Random ActiveSync clients get a HTTP 500 Error.
The device log says "Err:Device not found", and the device doesn't 
continue to get synched.

Here the Device and Horde-Log of one happening, i hope i catched the 
relevant parts.
My horde installation is current with pear.

Device Log:

2016-01-14T11:48:37+01:00 INFO: [53178] Fetching changes for calendar 
using MODSEQ.
2016-01-14T11:48:37+01:00 INFO: [53178] Found 0 message changes in 
A16da253e.
2016-01-14T11:48:37+01:00 INFO: [53178] Sleeping for 15 seconds.
2016-01-14T11:48:52+01:00 INFO: [53178] SyncCache collections refreshed.
2016-01-14T11:48:52+01:00 INFO: [53178] Refreshing T757f5b8b from the cache.
2016-01-14T11:48:52+01:00 INFO: [53178] Refreshing N0960efa7 from the cache.
2016-01-14T11:48:52+01:00 INFO: [53178] Refreshing Feabe7c82 from the cache.
2016-01-14T11:48:52+01:00 INFO: [53178] Refreshing F7d55008a from the cache.
2016-01-14T11:48:52+01:00 INFO: [53178] Refreshing Ccde63f9f from the cache.
2016-01-14T11:48:52+01:00 INFO: [53178] Refreshing A16da253e from the cache.
2016-01-14T11:48:52+01:00 ERR: Device not found.

Horde Log:

7 {main} [pid 53793 on line 165 of 
"/usr/share/php5/PEAR/Horde/Rpc/ActiveSync.php"]
2016-01-14T11:46:48+01:00 ERR: HORDE Buffer contents:  [pid 53793 on 
line 165 of "/usr/share/php5/PEAR/Horde/Rpc/ActiveSync.php"]
2016-01-14T11:47:33+01:00 NOTICE: HORDE [imp] Login success for xxxxxx 
(y.y.y.y) to {imap://localhost/} [pid 50760 on line 157 of 
"/srv/www/eyeos/horde4/imp/lib/Auth.php"]
2016-01-14T11:47:37+01:00 NOTICE: HORDE [imp] Login success for xxxxxx 
(y.y.y.y) to {imap://localhost/} [pid 53178 on line 157 of 
"/srv/www/eyeos/horde4/imp/lib/Auth.php"]
2016-01-14T11:48:52+01:00 ERR: HORDE Returning HTTP 500 while handling 
Ping command. Error is: Device not found. [pid 53178 on line 160 of 
"/srv/www/eyeos/horde4/rpc.php"]
2016-01-14T11:48:52+01:00 ERR: HORDE Error in communicating with 
ActiveSync server: Device not found. [pid 53178 on line 165 of 
"/usr/share/php5/PEAR/Horde/Rpc/ActiveSync.php"]
2016-01-14T11:48:52+01:00 ERR: HORDE #0 
/usr/share/php5/PEAR/Horde/ActiveSync/State/Base.php(215): 
Horde_ActiveSync_State_Sql->loadDeviceInfo('xxxxxx', 
'4E696E653343353...', Array)
#1 /usr/share/php5/PEAR/Horde/ActiveSync/Collections.php(1133): 
Horde_ActiveSync_State_Base->getDeviceRWStatus('4E696E653343353...', true)
#2 /usr/share/php5/PEAR/Horde/ActiveSync/Request/Ping.php(222): 
Horde_ActiveSync_Collections->pollForChanges('1680', 15, Array)
#3 /usr/share/php5/PEAR/Horde/ActiveSync/Request/Base.php(253): 
Horde_ActiveSync_Request_Ping->_handle()
#4 /usr/share/php5/PEAR/Horde/ActiveSync.php(803): 
Horde_ActiveSync_Request_Base->handle()
#5 /usr/share/php5/PEAR/Horde/Rpc/ActiveSync.php(143): 
Horde_ActiveSync->handleRequest('Ping', '4e696e653343353...')
#6 /srv/www/eyeos/horde4/rpc.php(160): 
Horde_Rpc_ActiveSync->getResponse(NULL)
#7 {main} [pid 53178 on line 165 of 
"/usr/share/php5/PEAR/Horde/Rpc/ActiveSync.php"]
2016-01-14T11:48:52+01:00 ERR: HORDE Buffer contents:  [pid 53178 on 
line 165 of "/usr/share/php5/PEAR/Horde/Rpc/ActiveSync.php"]

I already tried to re-create all horde_activesync_xx tables after all 
other measures ( Resetting sync in the webinterface, create account new 
on device) dind't help.
Any ideas what else i can try?

Thanks!

--Tom