GadgetField: py3

product/ERP5Form/GadgetField.py

+import io
 from Products.Formulator.Field import ZMIField
 from Products.Formulator import Widget
 from Products.Formulator.DummyField import fields
 from Products.Formulator import Validator
 from zLOG import LOG, ERROR
-from six.moves import cStringIO as StringIO
 from json import dumps
 from Acquisition import aq_base
 from six.moves.urllib.parse import urljoin
@@ -151,7 +151,7 @@ class GadgetFieldValidator(Validator.Validator):
         if value is not None:
           if field.get_value('data_url'):
             value=value.split(",")[1]
-            return StringIO(base64.b64decode(value))
+            return io.BytesIO(base64.b64decode(value))
           return value