PyDev + Eclipse Error Message. How to configure the Python interpreter

If you installed the PyDev plugin into Eclipse, you may get this message when you start up Eclipse:

An internal error occurred during: "PyDev code completion: rebuilding modules"

It means that, during the rebuilding of the Code Completion Tool, the Python interpreter has not been found. It happens when your Python system was not installed on the default folder (c:\Python); for example mine is installed in D:/Programs/Python. Yes I know, it's not a good practice and it's not suggested in the Python documention.


Solution:

How to set the Python system PYTHONPAT

Being into Eclipse you have to enter in "Window" menu, than "Preferences", "Pydev", "Interpreter-Python" and here you can configure your path. Click on "New..." on the left of "Python interpreters" window, and then choose your right python folder. In the shown up list, check every folder within your main python folder and go on.
Restart Eclipse.

P.S. You could also disable the "Code Completion Tool" rebuilding, but you loose this nice feature. Anyway, if you want to disable it, you can look into "Window-Preferences-Pydev-Builders" menu.