• There are some special cases which are not automatically converted. One of them is concatenating "str" and "bytes", in python2 this works, but in python3 you need to explicitly convert (encode/decode) one of them so that they are both "str" or "bytes"!
• Problem with trying to access a member called "None": In Python 3 you are not allowed to use access members called None. The example conversion macros linked above take care of this problem by using regex to replace the problematic parts as suggested here: https://github.com/IronLanguages/ironpython3/blob/v3.4.0/Documentation/upgrading-from-ipy2.md
• This is an example of the old and new syntax:
• #IronPython2 syntax:
  set = Zen.Processing.Filter.Settings.GaussSetting()
set.Dimension3rd.None
• #IronPython3 syntax:
  set = Zen.Processing.Filter.Settings.GaussSetting()
set.Dimension3rd["None"]