Question : Exchange 2003 active sync OWA HTTP/1.1 500 Internal Server Error

Hello,  
To start everything was working fine until about 8PM Sunday night.  For the past year our windows mobile 6.x phones have been syncing with no errors.  
Then it just stopped.  No updates or anything were done to the Frontend or backend exchange servers.  Also the mobile phones are the only thing not working.  OWA and https over RDP for outlook looks fine.  

Both servers are exchange 2003 SP2 with all service packs.  

On the windows mobile phone I get this error in the logs


=-=- [23/04/2009 08:51:0249.000] -=-=
=-=-=-= Client Request =-=-=-=
POST Microsoft-Server-ActiveSync?User=cluna&DeviceId=362513EE520DB0BF5B4640C10758FC7F&DeviceType=PocketPC&Cmd=FolderSync
Accept-Language: en-us
X-MS-PolicyKey: 0
MS-ASProtocolVersion: 2.5
Content-Type: application/vnd.ms-sync.wbxml
User-Agent: MSFT-PPC/5.2.1003

-=-=-=- Start of Body -=-=-=-
ync xmlns="FolderHierarchy:"><SyncKey>0</SyncKey></FolderSync>

=-=- [23/04/2009 08:51:0249.000] -=-=
=-=-=-= Server Response =-=-=-
HTTP/1.1 500 Internal Server Error
Date: Thu, 23 Apr 2009 15:51:41 GMT
Server: Microsoft-IIS/6.0
X-Powered-By: ASP.NET
Pragma: no-cache
Content-Type: text/html
Content-Length: 56
MS-Server-ActiveSync: 6.5.7638.1

And

2009-04-23 08:51:45      KeepAwake      On
2009-04-23 08:51:46      SyncBegin      http://schemas.microsoft.com/as/2004/core" type="scheduled"/>
2009-04-23 08:51:46      EngineBegin      Microsoft Exchange, 2.5
2009-04-23 08:51:46      EstConnection      WOI NOT requested
2009-04-23 08:51:46      EstablishConn      hr=0x0, handle=0xc2ab021e, pri=0x200, status=0x10, flags=0x400000, wait=0
2009-04-23 08:51:46      ConnInfo      Type=1, Subtype=1, Secure=0, Descr=Data Network Connect
2009-04-23 08:51:48      AutdMode      Old=Not Determined, New=Not Determined
2009-04-23 08:51:49      DormantHint      Dormant mode on [Sync]
2009-04-23 08:51:49      EngineEnd      hr=0x85010014, ActiveSync encountered a problem on the %1!s!.
2009-04-23 08:51:49      RetrySync      in 15 mins, retry number 82, case: Retry, reached Max Interval
2009-04-23 08:51:49      SyncEnd      
2009-04-23 08:51:49      AutdMode      Old=Not Determined, New=Not Determined
2009-04-23 08:51:49      Scheduled      2009-04-23 09:06:49, handle=0x3d00001d, hr=0x0
2009-04-23 08:51:50      KeepAwake      Off

Any ideas?

Answer : Exchange 2003 active sync OWA HTTP/1.1 500 Internal Server Error

Things don't stop working suddenly for no reason, so something must have changed. Have you checked the SSL certificate hasn't expired?

Use a test account with the Microsoft test site and see what that throws up:
https://testexchangeconnectivity.com/

Simon.