Why does PyQt5 hang on Ubuntu 14.04?

Question

Python

Welcome all.
There are several homemade progs on PyQt5. Everything was fine under gentoo , but the computer broke down and I had to transfer to my wife's machine, where ubuntu 14.04 . I put all the modules and ... And none of my programs work.

PyQt5

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import re
import sys
import warnings
import os
import lxml.etree as et
from PyQt5 import (QtCore, QtGui, uic, QtWidgets)
from PyQt5.QtWidgets import (QMainWindow, QTextEdit, QAction, QFileDialog, QApplication, QProgressBar)
from PyQt5.QtGui import QIcon
from PyQt5.QtCore import *

warnings.filterwarnings("ignore")
cwd = os.path.expanduser('~')

filename = 'converter.ui'
filename = cwd + "/codding/Convert-fb2/" + filename
Form, Base = uic.loadUiType(filename)

class MyWindow(QtWidgets.QWidget, Form):
    def __init__(self, parent=None):
        QtWidgets.QWidget.__init__(self, parent)
        self.ui = Form()
        self.ui.setupUi(self)
        self.timer = QBasicTimer()
        self.step = 0
        self.ui.btnQuit.clicked.connect(QCoreApplication.instance().quit)
        self.ui.showd.clicked.connect(self.getfiles)
        self.ui.btnConv.clicked.connect(self.convertfiles)
        
    def getfiles(self):

        fname = QFileDialog.getOpenFileName(self, "Open fb2", "/home/", "FictionBook Files (*.fb2)")[0]
        if fname == '':
            QFileDialog(self, quit())
       
        with open(fname, 'r') as data:
            data = data.read()
            self.ui.textIn.setText(data)
            self.ui.mylabel.setText('Input file: ' + fname)
        global fout
        fout = re.sub(r'\.fb2', '', fname)
        fout = fout + '.txt'

        with open(fname, 'rb') as f_in, open(fout, 'w') as f_out:
            check = f_in.read()
            tree = et.fromstring(check)
            ns = {'ns': "http://www.gribuser.ru/xml/fictionbook/2.0"}
            for bin_eb in tree.xpath('//ns:binary', namespaces=ns):
                bin_eb.getparent().remove(bin_eb)
            for bin_ed in tree.xpath('//ns:description', namespaces=ns):
                bin_ed.getparent().remove(bin_ed)
            global cleart, cleart2
            cleart = et.tounicode(tree)
            cleart = re.sub(r'\<[^>]*\>', '', cleart)

            self.ui.textOut.setText(cleart)

    def convertfiles(self):
        if self.ui.textOut.toPlainText() == '' or self.ui.textIn.toPlainText() == '':
            self.ui.textOut.setText('ОТКРОЙ ФАЙЛ!')
        else:
            cleart2 = self.ui.textOut.toPlainText()
            self.ui.mylabel.setText('')
            with open(fout, 'w') as f_out:
                f_out.write(cleart2)
                self.ui.mylabel.setText('Saved file: ' + fout)

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    window = MyWindow()
    window.setWindowTitle("Ковертер Fb2 > Txt")
    window.setWindowIcon(
        QtGui.QIcon(cwd + "/codding/Convert-fb2/" + 'icon.png'))
    window.show()
    sys.exit(app.exec_())

Hangs tight.
Exhaust here
And here PyQt4 works fine

PyQt4 code

#!/usr/bin/env python3.4
# -*- coding: utf-8 -*-

import re
import sys
import warnings
import lxml.etree as et
from PyQt4 import (QtCore, QtGui, uic)
from PyQt4.QtGui import QIcon
from PyQt4.QtGui import QFileDialog
from PyQt4.QtCore import *

warnings.filterwarnings("ignore")

Form, Base = uic.loadUiType("/home/fil/codding/Convert-fb2/converter.ui")

class MyWindow(QtGui.QWidget, Form):
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)
        self.ui = Form()
        self.ui.setupUi(self)
        self.timer = QBasicTimer()
        self.step = 0
        self.ui.btnQuit.clicked.connect(QCoreApplication.instance().quit)
        self.ui.showd.clicked.connect(self.getfiles)
        self.ui.btnConv.clicked.connect(self.convertfiles)
        self.setGeometry(400, 200, 1000, 420)

    def getfiles(self):

        fname = QtGui.QFileDialog.getOpenFileName(self, "Open fb2", "/home/fil/", "FictionBook Files (*.fb2)")
        print (fname)

        with open(fname, 'r') as data:
            data = data.read()
            self.ui.textIn.setText(data)
            self.ui.mylabel.setText('Input file: ' + fname)

        global fout
        fout = re.sub(r'\.fb2', '', fname)
        fout = fout + '.txt'

        with open(fname, 'rb') as f_in, open(fout, 'w') as f_out:
            check = f_in.read()
            tree = et.fromstring(check)
            ns = {'ns': "http://www.gribuser.ru/xml/fictionbook/2.0"}
            for bin_eb in tree.xpath('//ns:binary', namespaces=ns):
                bin_eb.getparent().remove(bin_eb)
            for bin_ed in tree.xpath('//ns:description', namespaces=ns):
                bin_ed.getparent().remove(bin_ed)
            global cleart, cleart2
            cleart = et.tounicode(tree)
            cleart = re.sub(r'\<[^>]*\>', '', cleart)
            self.ui.textOut.setText(cleart)

    def convertfiles(self):
        cleart2 = self.ui.textOut.toPlainText()
        self.ui.mylabel.setText('')
        with open(fout, 'w') as f_out:
            f_out.write(cleart2)
        self.ui.mylabel.setText('Saved file: ' + fout)
        print(fout)

if __name__ == "__main__":
    import sys
    app = QtGui.QApplication(sys.argv)
    window = MyWindow()
    window.setWindowTitle("Ковертер Fb2 > Txt")
    window.setWindowIcon(
        QtGui.QIcon('skull.png'))
    window.show()
    sys.exit(app.exec_())

How to win?
Thank you.