TaxonomyField.SetFieldValue throws “Specified method is not supported” Exception

Question

I'm trying to copy a list item from one list to another. The lists are on the same site and the code is being fired inside of an item added/updated event receiver).

Both lists have managed metadata fields mapped to the same term sets.

Everything works as excepted until I try to set the Managed Metadata fields.

            SPListItem newItem = destinationList.Items.Add();
            newItem["Title"] = oldItem.Title;
            //Assign the rest of the non-taxonomy field values
            newItem.Update(); 
            SetTaxononmyField(newItem, myTaxonomyFieldValue, "fieldname");
            newItem.Update();

-

    private void SetTaxononmyField(SPListItem newItem, TaxonomyFieldValue value, string fieldname)
    {
        TaxonomyField field = newItem.Fields.GetFieldByInternalName(fieldname) as TaxonomyField;
        if (field != null)
        {
            field.SetFieldValue(newItem, value);//Throws "Specified method is not supported" exception here
        }
    }

Answer 1

The issue disappeared when I created a custom content type for the destination list. The code from above changes slightly to set the SPListItem content type.

            //retrieve and set the content type
            SPContentType contentType = destinationList.ContentTypes["ContentTypeName"];
            SPListItem newItem = destinationList.Items.Add();
            newItem["ContentTypeId"] = contentType.Id;
            newItem.Update();

If anyone could shed some light on why I had to do this I'd appreciate it.

Answer 2

I had the same problem today when copying. Difference for me I was copying from one column to another. Both columns were managed metadata columns pointing to the same managed metadata.

The reason I kept getting the error was because the column I read in was a Managed Metadata that allowed multiple values, the second column didn't. Therefore Specified Method was not supported because I was trying to add a TaxonomyFieldValueCollection to a column that only expected a TaxononomyFieldValue.

Looking at the code above, you might have been doing it the other way round. A TaxonomyFieldValue into a TaxonomyFieldValueCollection column.