PyQt GUI doesn't appear at Raspberry Pi startup

[PyQtN00b]

Hey Guys,
I am trying to get this running for days.
I created a simple PyQt-Script With two buttons and a label.
When I start it on my Raspberry Pi via consolse it works fine.
I edited the rc.local file on my Pi to make it running ont startup.
(btw I also tried all the other possibilities like .desktop-file or editing autostart file in lxsession)
When I reboot the Pi (autologin on desktop) the GUI doesnt appear.
But the python-script was executed (I know it, because it's also writing the time in a file)
And when I try the same with a simple py-script using kivy it works perfectly.

Do you have any suggestions what I do wrong?

Thanks in advance!

btw. I am using a Raspberry Pi 2 B with Raspbian Jessie on an original Raspberry Pi 7" Touchscreen.
here is my python script:

#!/usr/bin/python
# always seem to need this
import sys
from time import *
 
# This gets the Qt stuff
import PyQt5
from PyQt5.QtWidgets import *
 
# This is our window from QtCreator
import mainwindow_auto
 
# create class for our Raspberry Pi GUI
class MainWindow(QMainWindow, mainwindow_auto.Ui_MainWindow):
 # access variables inside of the UI's file
	def __init__(self):
		super(self.__class__, self).__init__()
		self.setupUi(self) # gets defined in the UI file
 
# I feel better having one of these
def main():
 # a new app instance
	lt = localtime()
	zeitnow = strftime("Es ist: %H:%M:%S", lt)
	print (zeitnow)
	file = open("/home/pi/loggerfile.txt","w")
	file.write(zeitnow)
	file.close
	app = QApplication(sys.argv)
	form = MainWindow()
	form.show()
 # without this, the script exits immediately.
	sys.exit(app.exec_())
 
# python bit to figure how who started This
if __name__ == "__main__":
	main()

[SGaist]

Hi and welcome to devnet,

Do you already have the Xorg server running before starting your application ?

[PyQtN00b]

Hey,

thanks for you reply.
Yes I have the x server running.
I am using auto-login at desktop.

[jsulm]

@PyQtN00b You could try to redirect standard output and error output to a file when start your app:

PATH_TO_APP 2>&1 1 > PATH_TO_A_FILE

Then check the content of that file.

[sieciech]

Hi,

Suggestion: check the order of execution, and dependencies in execution script. Maybe you are trying to execute your app too soon, before drivers/configurations of display is set (To be honest, i don't know how does Linux handles loading of display drivers)

regards

[mvuori]

Another thing related to being executed too soon -- I would try adding a delay to the beginning of the script, say, like 5 seconds, to make sure the environment is ready.