After calling Py_Finalize and Py_Initialize I get the message "attribute of type 'NoneType' is not callable" on the datetime.strptime method.

Example:
from datetime import datetime
s = '20160505 160000'
refdatim = datetime.strptime(s, '%Y%m%d %H%M%S')

The first call works fine but it crashes after the re initialization.

Workaround:
from datetime import datetime
s = '20160505 160000'
try:
    refdatim = datetime.strptime(s, '%Y%m%d %H%M%S')
except TypeError:
    import time
    refdatim = datetime.fromtimestamp(time.mktime(time.strptime(s, '%Y%m%d %H%M%S')))

Related Issue: Issue17408 ("second python execution fails when embedding")