[sync] Outlook 2013 sync recovery after server down

[Tim ODriscoll]

Dear All,

Recently my Horde server stopped responding (due to no free inodes  
because /tmp/horde_form_* filled up), and it caused most (5 of 6)  
Outlook 2013 clients to loose sync. Outlook does not report any  
errors, but no new emails appear in Outlook, shared & personal  
calendar events disappear or fail to update.

I get various errors in the associated sync logs:
This on a client that was not uploading calendar changes:
ERR: [16751] Could not find state for synckey {xxxxxxxxxx}1.

This on a client that was not showing any calendar events or new emails:
ERR: [3776] Horde_ActiveSync_Collections::getBackendIdForFolderUid  
failed because folder was not found in cache

The only way to resolve the issue is to remove the client from the  
ActiveSync devices page within Horde and then remove and recreate the  
Outlook mail profile on the client.

I'm using Horde_ActiveSync v2.28.1

Every other ActiveSync client (iOS/Android) picked up the sync again  
after the server was fixed, so is it right to assume an Outlook  
setting is to blame?

Many thanks,

Tim