retro transformer.py issue

[Yingde]

I encountered the error message below when I ran transformer.py individually.
INFO@retro_transformer : [1.278s] Loading precursor prioritizer for RetroTransformer
INFO@pricer : [2.305s] Cannot connect to mongodb to load prices
INFO@pricer : [3.839s] Loaded prices from flat file
INFO@retro_transformer : [3.846s] Loading fast filter for RetroTransformer
INFO@fast_filter : [3.861s] Starting to load fast filter
INFO@fast_filter : [5.480s] Done loading fast filter
INFO@retro_transformer : [5.497s] Using default clustering for RetroTransformer
INFO@pricer : [6.543s] Cannot connect to mongodb to load prices
INFO@pricer : [7.897s] Loaded prices from flat file
INFO@retro_transformer : [7.913s] Loading retro-synthetic transformer
INFO@retro_transformer : [7.928s] reading from file
INFO@template_transformer: [7.942s] Loading templates from askcos-core/askcos/data/templates/retro.templates.json.gz
INFO@template_transformer: [14.288s] Loaded templates. Using 163723 templates
[(1, 'CCOC(=O)[C@H]1CC@@HC@@HN1', 109659, [], 0.0)]

Thanks