Conflict note data while fetchFilteredSyncChunk

[lijuncode]

func syncChunkFilter() -> EDAMSyncChunkFilter {
    let filter = EDAMSyncChunkFilter()
    filter.includeNotes = NSNumber(value: true)
    filter.notebookGuids = Set(arrayLiteral: bookGuid)
    return filter
  }

storeClient.fetchFilteredSyncChunk(afterUSN: 39370, maxEntries: 99999, filter: syncChunkFilter()) { (chunk, error) in
      if let chunk = chunk {
        printLog(message: "\(chunk)")
      }

      if let error = error {
        printLog(message: error.localizedDescription)
      }
    }

If I set the notebookGuids, it thrown the error:

Error Domain=ENErrorDomain Code=8 "Conflict note data." 
UserInfo={NSLocalizedDescription=Conflict note data., EDAMErrorCode=10, parameter=notebookFilter}

if I don't set the notebookGuids, it don't thrown this error, and can fetch the syncChunk success. why?