I have not seen this error yet. But I have found the same message in a discussion at [1] - maybe it will help you?

[1] https://mail.enthought.com/pipermail/enthought-dev/2010-February/025433.html

I did go through it. It says that some module is importing wx before the version change is performed.

 import wxversion
---> 21 wxversion.select("2.8")
     22 import wx

Only after the version is selected, wx is imported. It is getting imported before.