screenmanagererror.kv

#:kivy 1.5.1
#:import kivy kivy
 
<ScreenOne>:
    GridLayout:
        size: root.size
        rows: 3

        Label:
            text: 'Screen One'
 
        TextInput:
            id: text_screen_one
 
        Button:
            text: 'Go to Screen Two'
            on_press: root.manager.current = 'screentwo'
 
 
<ScreenTwo>:
    GridLayout:
        size: root.size
        rows: 3
 
        Label:
            text: 'Screen Two'
 
        TextInput:
            id: text_screen_two
            focus: True
 
        Button:
            text: 'Go to Screen One'
            on_press: root.manager.current = 'screenone'

ScreenManagerError.py

from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
 
class ScreenOne(Screen):
    pass
 
class ScreenTwo(Screen):
    pass
 
class ScreenManagerErrorApp(App):
 
    def build(self):
 
        sm = ScreenManager()
        sm.add_widget(ScreenOne(name='screenone'))
        sm.add_widget(ScreenTwo(name='screentwo'))
 
        return sm
 
if __name__ == '__main__':
    ScreenManagerErrorApp().run()