Outlook : Conflict while saving contact - sharepoint

Question

I am working on a project involving contact synchronization between Outlook and SharePoint. Though there is an out of the box solution provided for this by Microsoft, but it does not cater some specific requirements like custom column synchronization.
For this requirement we had to create an outlook add-in. This add-in handles ItemAdd and ItemChange event for the contact folder created as a result of the synchronization.
In the ItemChange event I check a flag in the Notes field and identify whether the change has been made from SharePoint or Outlook and accordingly update the contact item.
Here is the code for my ItemChange event.
void Items_ItemChange(object Item)
{
try
{
ContactItem ctItem = Item as Outlook.ContactItem;
string customFieldsAndFlag = ctItem.Body;
Dictionary<string, string> customColumnValueMapping = new Dictionary<string, string>();
if (!string.IsNullOrEmpty(customFieldsAndFlag))
{
string[] flagAndFields = customFieldsAndFlag.Split(';');
if (flagAndFields.Length == 2)
{
//SharePoint to Outlook
if (flagAndFields[0] == "1")
{
foreach (string customColumnAndValue in flagAndFields[1].Split('|'))
{
string[] KeyAndValue = customColumnAndValue.Split('=');
if (KeyAndValue.Length == 2)
{
if (ctItem.UserProperties[KeyAndValue[0]] == null)
{
ctItem.UserProperties.Add(KeyAndValue[0], OlUserPropertyType.olText, true, OlUserPropertyType.olText);
ctItem.UserProperties[KeyAndValue[0]].Value = KeyAndValue[1];
}
else
{
ctItem.UserProperties[KeyAndValue[0]].Value = KeyAndValue[1];
}
}
}
ctItem.Body = "2;" + flagAndFields[1];
}
//Outlook to SharePoint
else
{
foreach (string customColumnAndValue in flagAndFields[1].Split('|'))
{
string[] KeyAndValue = customColumnAndValue.Split('=');
if (KeyAndValue.Length == 2)
{
if (ctItem.UserProperties[KeyAndValue[0]] != null && ctItem.UserProperties[KeyAndValue[0]].Value != null)
{
KeyAndValue[1] = ctItem.UserProperties[KeyAndValue[0]].Value.ToString();
}
customColumnValueMapping.Add(KeyAndValue[0], KeyAndValue[1]);
}
}
string newBody = string.Empty;
foreach (KeyValuePair<string, string> kvp in customColumnValueMapping)
{
newBody += kvp.Key + "=" + kvp.Value + "|";
}
if (newBody == flagAndFields[1])
{
return;
}
else
{
ctItem.Body = "0;" + newBody;
}
}
}
}
ctItem.Save();
}
catch(System.Exception ex)
{
// log the error always
Trace.TraceError("{0}: [class]:{1} [method]:{2}\n[message]:{4}\n[Stack]:\n{5}",
DateTime.Now, // when was the error happened
MethodInfo.GetCurrentMethod().DeclaringType.Name, // the class name
MethodInfo.GetCurrentMethod().Name, // the method name
ex.Message, // the error message
ex.StackTrace // the stack trace information
);
// now display a friendly error to the user
MessageBox.Show("There was an application error, you should save your work and restart Outlook.",
"TraceAndLog",
MessageBoxButtons.OK,
MessageBoxIcon.Error);
}
}
Now the issue is, the contact item update works fine from outlook the first time. The contact gets updated properly, the add-in works fine and changes get reflected in SharePoint just fine. But when I try to edit the contact again using outlook, a pop-up comes up saying "Item cannot be changed because it was changed by another user or in another window. Do you want to make a copy in the default folder for the item?" and the oulook add-in stops working thereafter.
Can anyone please suggest a solution for this problem?
I cannot use ctItem.Close() as when I use this function, the synchronization process doesn't work and the changes don't get populated to SharePoint.