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Everything was running fine, until I restarted the server (there may have been some updates installed as well during that restart) and now I can't connect to retrieve mail and Administrator comes up with this exception when I try to view the status:

The RPC server is unavailable. (Exception from HRESULT: 0x800706BA)

ExceptionType: COMException
Message: The RPC server is unavailable. (Exception from HRESULT: 0x800706BA)
Source: Interop.hMailServer
StackTrace:    at hMailServer.LanguageClass.get_String(String EnglishString)
   at hMailServer.Administrator.Strings.Translate(String text)
   at hMailServer.Administrator.Strings.Localize(Control container)
   at hMailServer.Administrator.ucStatus..ctor()
   at hMailServer.Administrator.Nodes.NodeStatus.CreateControl()
   at hMailServer.Administrator.formMain.ShowNodeRepresentation(INode node)
   at hMailServer.Administrator.formMain.treeNodes_AfterSelect(Object sender, TreeViewEventArgs e)
   at System.Windows.Forms.TreeView.OnAfterSelect(TreeViewEventArgs e)
   at System.Windows.Forms.TreeView.TvnSelected(NMTREEVIEW* nmtv)
   at System.Windows.Forms.TreeView.WmNotify(Message& m)
   at System.Windows.Forms.TreeView.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
TargetSite: System.String get_String(System.String)

Since it was working before the restart I'm assuming it has something to do with components not starting up properly. RPC is running, so is SQL Server.

Windows Server 2008 hMailServer 5.3.3 B1879 MSSQL 2008

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Start with the obvious - the Windows event logs. Tell us what they say about the problem. Right now both you and us are working in a vacuum. – John Gardeniers Oct 7 '10 at 20:26

Have you verified that your SQL server is running? If it is running, you might check to ensure that you can connect to it and it is responding/responsive.

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up vote 0 down vote accepted

Ahh yes, I figured out the problem yesterday, forgot to post reply. I decided to reinstall hMailServer, just to see if that solved the problem (you never know, eh?) and it threw an error which was far more descriptive than this stack trace - server version was wrong.

I remembered during migration to a new server I also updated hMailServer to newer version, from 5.3.2 to 5.3.3. With it I had to migrate the db as well, from MySQL to MSSQL. Everything went fairly well, but I remembered changing a value in hm_dbversion table from 5320 to 5330, assuming it should reflect hMailServer version. Oddly enough it was working fine until SQL Server was restarted, at which point it failed to connect. Changing it back to 5320 solved the problem.

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