Error copying theme in Theming control panel

I am using this setup

Plone 5.2.1 (5208)
CMF 2.4.2
Zope 4.1.3
Python 2.7.15+ (default, Nov 27 2018, 23:36:35) [GCC 7.3.0]
PIL 6.2.1 (Pillow)
Server: waitress 1.4.2

When I try to copy a theme in the Theming control panel I get the following error. I'm looking for hints as to the cause. Thanks :slight_smile:

Traceback (innermost last):
  Module ZPublisher.WSGIPublisher, line 156, in transaction_pubevents
  Module ZPublisher.WSGIPublisher, line 338, in publish_module
  Module ZPublisher.WSGIPublisher, line 256, in publish
  Module ZPublisher.mapply, line 85, in mapply
  Module ZPublisher.WSGIPublisher, line 62, in call_object
  Module, line 57, in __call__
  Module, line 370, in update
  Module, line 517, in createThemeFromTemplate
  Module plone.resource.utils, line 99, in cloneResourceDirectory
  Module, line 91, in openFile
  Module, line 97, in readFile
IOError: u'b'

Ui, a unicode :honeybee:!

I am pretty sure I didn't enter any Unicode in the name or description of the copied theme... maybe there is in the name of one of the resources being copied. I will step through the code...

That's not a unicode error, thats the py2.7 representation of a unicode string which likely should be encoded to get bytes instead.