ModuleNotFoundError: Python 3.6 does not find modules while Python 3.5 does

Question

I wanted to upgrade my python version from 3.5 to 3.6. Since I am using WinPython, I have downloaded and installed the recent version just as I did it before with version 3.5.

However, if I use version 3.6 I get a ModuleNotFoundError whenever I import a self-created module. A minimal example: I created a file t1.py that contains only a pass statement and a file t2.py containing the following code:

import t1
print("done")

Both files are in the same folder D:\MyProject\src. Now when I run the file with python 3.5, everything works fine:

'C:\Program Files\WinPython-64bit-3.5.1.2\python-3.5.1.amd64\python.exe' D:\MyProject\src\t2.py
done

However, with python 3.6 I get

'C:\Program Files\WinPython-64bit-3.6.0.1Qt5\python-3.6.0.amd64\python.exe' D:\MyProject\src\t2.py
Traceback (most recent call last):
  File "D:\MyProject\src\t2.py", line 6, in <module>
    import t1
ModuleNotFoundError: No module named 't1'

I ran out of ideas what the issue could be and would appreciate new inspiration.

Answer 1

Would this work ? in t2.py

import os
__path__=[os.path.dirname(os.path.abspath(__file__))]
from . import t1
print("t2 done")

Python-3.6 changes its way of working, with the "python._pth" file next to python.exe (instead of "pyvenv.cfg" in previous versions)

If you don't want to modify your source, then you have to add "D:\MyProject\src" line in Python._pth file, or a relative path to it from python._pth location. in my example, it works with:

python36.zip
DLLs
Lib
.
..\test
import site

"http://bugs.python.org/issue29578?@ok_message=msg%20287921%20created%0Aissue%2029578%20message_count%2C%20messages%20edited%20ok&@template=item"

Other, simpler solution if you have no system-installed python: rename the "python._pth" file, next to "python.exe", as "pythonzz._pth"

The Python "Windows" maintainer just wrote that the simpler solution should be ok also with Python-3.6.0.