It was asked at Stackoverflow. http://stackoverflow.com/questions/33631652/converting-to-jython-a-python-3-5-project-unicodedecodeerror-unicodeescape Details: •The latest Jython is 2.7 •The project I have is runnable with Python 3.5 So I took the following approach: First thing was to convert my project to Python 2.7 utilizing the future module and pasteurize executable. This step was done successfully. Second thing is to convert the Python 2.7 project to a Jython 2.7 Project. Here it wasn't possible to do so because of a surrogateecape problem.