Cannot get data from Materials Project by chemical formula or chemsys

Hi, I met the following problem as I try to get data from Materials Project at present. It seems to be a common problem if chemical formula (Fe2O3) or chemsys (Fe-O) is used for vasp data. Thank you.


“valid_response”: false,
“error”: “‘NoneType’ object is not iterable”,


Hi, is using pymatgen not an option?

from pymatgen import MPRester

with MPRester() as mpr:
    id_list = mpr.query(criteria={'pretty_formula': "Fe2O3"},

works fine. Of course you can query for the properties you want to know…

Sorry if that is not what you are looking for…

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@Takeshi_Miyake this appears related to a code/configuration bug in the latest release (Querying phase diagram data):

This appears to be a bug in the latest updated on our server where it is not by default only querying valid materials. The result is you’re getting deprecated materials that fail in this way. We’re working on fixing this issue.

This should be fixed now.