A duplicate field name "GUID" found when adding custom content type to custom list

Question

I've created a custom list with one content type inherited from 'Schedule' (no additional fields). Now I need to add one more content type to the instance of that list in the feature activated event (this content type is also inherited from 'Schedule' and has some additional fields including several taxonomy fields).

the following piece of code: myCustomList.ContentTypes.Add(myCustomContentType); generates the following error: A duplicate field name "{78190EDB-029C-42d3-A22A-498FE43D9EC0}" was found.

Piece of stack trace:

[SPException: A duplicate field name "78190edb-029c-42d3-a22a-498fe43d9ec0" was found.]
   Microsoft.SharePoint.SPFieldLinkCollection.Add(SPFieldLink fieldLink) +1445
   Microsoft.SharePoint.SPContentType.UpdateFieldsCollection(Dictionary`2 cachedFields, Guid addedField) +521
   Microsoft.SharePoint.SPContentType.ProvisionFieldOnList(SPField field, Boolean bRecurAllowed) +2355
   Microsoft.SharePoint.SPContentType.ProvisionFieldsOnList() +634
   Microsoft.SharePoint.SPContentType.DeriveContentType(SPContentTypeCollection cts, SPContentType& ctNew) +671
   Microsoft.SharePoint.SPContentTypeCollection.AddContentTypeToList(SPContentType contentType) +2319
   Microsoft.SharePoint.SPContentTypeCollection.AddContentType(SPContentType contentType, Boolean updateResourceFileProperty, Boolean checkName, Boolean setNextChildByte) +242
   Microsoft.SharePoint.SPContentTypeCollection.Add(SPContentType contentType) +24
   Microsoft.SharePoint.ApplicationPages.AddContentTypeToListPage.Update(Object o, EventArgs e) +835
   System.Web.UI.WebControls.Button.OnClick(EventArgs e) +103
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +140
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +32
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3103

The 'GUID' is a GUID of a taxonomy hidden text field. Here is it:

<Field ID="{78190EDB-029C-42d3-A22A-498FE43D9EC0}"
       Name="MyTaxonomyFieldNameTaxHTField0"
       StaticName="MyTaxonomyFieldNameTaxHTField0"
       DisplayName="MyTaxonomyFieldNameTaxHTField0"
       Group="MyGroupName"
       Type="Note"
       ShowInViewForms="FALSE"
       CanToggleHidden="TRUE"
       Hidden="TRUE"/>

I tried recreating the whole web application, changing the GUID of the field...the same thing occurs with any taxonomy hidden text field included in content type (and it doesn't matter if I'm doing it programmatically or through the web. All taxonomy fields itself are activated properly.

Answer 1

I have stumbled upon a similar issue and found a workaround for the issue. What I did was write a loop that tries to create the column and with a try catch construction, removes the duplicate column in the catch clause. I encountered the issue when trying to create a taxonomy site column with the same description as an existing column.

bool createSucceeded = false;
while (!createSucceeded)
{
    try
        {
            field = _rootWeb.Fields.AddFieldAsXml(fieldXml, addToDefaultView, SP.AddFieldOptions.AddFieldInternalNameHint);
            ClientContext.ExecuteQuery();
            createSucceeded = true;
        }
    catch (ServerException ex)
    {
        if (ex.Message.Contains("A duplicate field name"))
        {
            var splitMessage = ex.Message.Split(new[] {'\"'}, StringSplitOptions.RemoveEmptyEntries);
            var duplicateName = splitMessage[1];
            DeleteSiteColumn(duplicateName);
        }
        else
        {
            throw;
        }
    }
}
public void DeleteSiteColumn(string name)
{
    var siteColumn = _rootWeb.Fields.GetByInternalNameOrTitle(name);
    if (siteColumn == null) return;
    siteColumn.DeleteObject();
    ClientContext.ExecuteQuery();
}