Well, this has nothing to do with SyncML then, and you might have to 
track this down yourself, if you want to help development by using 
bleeding-edge versions.

I updated to the latest CVS and GIT Versions.  Maybe it´s something in 
IMP wich causes the problem. The last SyncML Problem had something to 
do with the authentication API of IMP.

And what *did* you change in Horde?

I am using the HEAD Version of Horde and Synthesis SyncML Client. 
Things worked well till I tried to sync yesterday. All I got was an 
10400 error by synthesis. I am not sure wether this is a horde or a 
Synthesis problem, but as the Synthesis client hasn´t changed but 
horde has, I suspect the problem is with horde. I tried normal sync, 
slow sync and reload device. They all endet in 10400



The debug output of the sync attempt looks like this (I deleted the 
server adress):



DEBUG:  Backend of class SyncML_Backend_Horde created

DEBUG:  Started at 2009-03-08 22:01:03. Packet logged in 
/tmp/sync/client_40.wbxml

DEBUG:  New session created: 61cdd18d69b195ead3111799095ae1d6

DEBUG:  Checking authentication for user twilek

DEBUG:  Authenticated: yes; version: 1.2; message ID: 1; source URI: 
AEA7F7C0463D73482F56406B6009D059F7CE53D9; target URI: 
http://xxx.de/rpc.php; user: twilek; charset: UTF-8; wbxml: yes

DEBUG:  SQL Query by SyncML_Backend_Horde::eraseMap(): DELETE FROM 
horde_syncml_map WHERE syncml_syncpartner = ? AND syncml_db = ? AND 
syncml_uid = ?, values: AEA7F7C0463D73482F56406B6009D059F7CE53D9, 
calendar, twilek

DEBUG:  Creating SyncML_Sync object for database calendar; sync type 201

DEBUG:  SQL Query by SyncML_Backend_Horde::eraseMap(): DELETE FROM 
horde_syncml_map WHERE syncml_syncpartner = ? AND syncml_db = ? AND 
syncml_uid = ?, values: AEA7F7C0463D73482F56406B6009D059F7CE53D9, 
tasks, twilek

DEBUG:  Creating SyncML_Sync object for database tasks; sync type 201

DEBUG:  SQL Query by SyncML_Backend_Horde::eraseMap(): DELETE FROM 
horde_syncml_map WHERE syncml_syncpartner = ? AND syncml_db = ? AND 
syncml_uid = ?, values: AEA7F7C0463D73482F56406B6009D059F7CE53D9, 
contacts, twilek

DEBUG:  Creating SyncML_Sync object for database contacts; sync type 201

DEBUG:  Received <Final> from client.

DEBUG:  Handle <Final> for state Init

DEBUG:  Handle <Final> for state Init

DEBUG:  Handle <Final> for state Init

DEBUG:  Sending <Final> to client

DEBUG:  Return message completed

DEBUG:  Finished at 2009-03-08 22:01:08. Packet logged in 
/tmp/sync/server_40.wbxml



DEBUG:  Backend of class SyncML_Backend_Horde created

DEBUG:  Started at 2009-03-08 22:01:12. Packet logged in 
/tmp/sync/client_41.wbxml

DEBUG:  New session created: 61cdd18d69b195ead3111799095ae1d6

DEBUG:  Invalid authentication

DEBUG:  Authenticated: no; version: 1.2; message ID: 2; source URI: 
AEA7F7C0463D73482F56406B6009D059F7CE53D9; target URI: 
http://xxx.de/rpc.php; user: twilek; charset: UTF-8; wbxml: yes

DEBUG:  Received <Final> from client.

DEBUG:  Sending <Final> to client

DEBUG:  Session completed and closed

DEBUG:  Finished at 2009-03-08 22:01:12. Packet logged in 
/tmp/sync/server_41.wbxml



Somehow with the second connect the authentication seems to fail.

I let IMP handle the authentication for horde. I have cleared my phone 
memory and erased the SyncML Sessions with horde but to no avail.