PyQt4 and PyQt5 collisions in PyCharm 2017.2.1 when debugging QGIS application

I have resolved the problem. Here is how I did so.

A dependency of my code loads matplotlib, which causes the pycharm debugger to load its internal module matplotlibtools.py. This attempts to enable the GUI interactive event loop via the do_enable_gui function:

import sys

backends = {'tk': 'TkAgg',
            'gtk': 'GTKAgg',
            'wx': 'WXAgg',
            'qt': 'Qt4Agg', # qt3 not supported
            'qt4': 'Qt4Agg',
            'qt5': 'Qt5Agg',
            'osx': 'MacOSX'}

# We also need a reverse backends2guis mapping that will properly choose which
# GUI support to activate based on the desired matplotlib backend.  For the
# most part it's just a reverse of the above dict, but we also need to add a
# few others that map to the same GUI manually:
backend2gui = dict(zip(backends.values(), backends.keys()))
backend2gui['Qt4Agg'] = 'qt4'
backend2gui['Qt5Agg'] = 'qt5'
# In the reverse mapping, there are a few extra valid matplotlib backends that
# map to the same GUI support
backend2gui['GTK'] = backend2gui['GTKCairo'] = 'gtk'
backend2gui['WX'] = 'wx'
backend2gui['CocoaAgg'] = 'osx'


def do_enable_gui(guiname):
    from _pydev_bundle.pydev_versioncheck import versionok_for_gui
    if versionok_for_gui():
        try:
            from pydev_ipython.inputhook import enable_gui
            enable_gui(guiname)
        except:
            sys.stderr.write("Failed to enable GUI event loop integration for '%s'\n" % guiname)
            import traceback
            traceback.print_exc()
    elif guiname not in ['none', '', None]:
        # Only print a warning if the guiname was going to do something
        sys.stderr.write("Debug console: Python version does not support GUI event loop integration for '%s'\n" % guiname)
    # Return value does not matter, so return back what was sent
    return guiname

The backend is determined by the system default. It turns out that it is sufficient to set the backend explicitly in code to avoid this error. Adding

import matplotlib
matplotlib.rcParams['backend'] = 'Qt4Agg'
matplotlib.rcParams['backend.qt4'] = 'PyQt4'

to the beginning of my main module resolves the issue.

On Ubuntu 16.04.3 LTS with installed the following versions of Qt:

qt4-x86_64-linux-gnu
qt5-x86_64-linux-gnu

I had to change Qt4 to Qt5:

import matplotlib
matplotlib.rcParams['backend'] = 'Qt5Agg'
matplotlib.rcParams['backend.qt5'] = 'PyQt5'

Dear colleagues,

Please Help.

1. I add Path according to instruction https://github.com/USEPA/SWMM-EPANET_User_Interface/wiki/Getting-Started-as-a-Developer-in-Python-3

If I start and try import qgis I receive error: 

2. I start with python-qgis.bat file with:

@echo off
call C:\OSGeo4W64\bin\o4w_env.bat
call qt5_env.bat
call py3_env.bat
@echo off
path %OSGEO4W_ROOT%\apps\qgis\bin;%PATH%;
set QGIS_PREFIX_PATH=%OSGEO4W_ROOT:\=/%/apps/qgis
set GDAL_FILENAME_IS_UTF8=YES
rem Set VSI cache to be used as buffer, see #6448
set VSI_CACHE=TRUE
set VSI_CACHE_SIZE=1000000
set QT_PLUGIN_PATH=%OSGEO4W_ROOT%\apps\qgis\qtplugins;%OSGEO4W_ROOT%\apps\qt5\plugins
set PYTHONPATH=%OSGEO4W_ROOT%\apps\qgis\python;%PYTHONPATH%;
rem "%PYTHONHOME%\python" %*

@"C:\Program Files\JetBrains\PyCharm 2018.2\bin\pycharm64.exe"

Then I run program with Ctr+Shift+F10 everything is ok, program run. 

But if I try start debugging I received error:

Please help...

Thanks in advance!