Debug kivy MarkupLabel

demo.py

import kivy
kivy.require('1.6.0') # replace with your current kivy version !

from kivy.app import App
from kivy.uix.label import Label

class MyApp(App):
    def build(self):
        return Label(text='Hello World', markup=True)

if __name__ == '__main__':
    MyApp().run()

log

$ python demo.py 
[INFO   ] Kivy v1.6.0
[INFO   ] [Logger      ] Record log in /Users/ihaque/.kivy/logs/kivy_13-04-03_48.txt
[INFO   ] [Factory     ] 137 symbols loaded
[DEBUG  ] [Cache       ] register <kv.lang> with limit=None, timeout=Nones
[DEBUG  ] [Cache       ] register <kv.image> with limit=None, timeout=60s
[DEBUG  ] [Cache       ] register <kv.atlas> with limit=None, timeout=Nones
[INFO   ] [Image       ] Providers: img_imageio, img_tex, img_dds, img_pygame, img_pil, img_gif 
[DEBUG  ] [Cache       ] register <kv.texture> with limit=1000, timeout=60s
[DEBUG  ] [Cache       ] register <kv.shader> with limit=1000, timeout=3600s
 /usr/local/lib/python2.7/site-packages/kivy/core/text/text_pygame.py:19: RuntimeWarning: use font: No module named font
 (ImportError: No module named font)
   pygame.font.init()
[DEBUG  ] [Text        ] Ignored <sdlttf> (import error)
[INFO   ] [Text        ] Provider: pil(['text_pygame', 'text_sdlttf'] ignored)
[DEBUG  ] [App         ] Loading kv <./my.kv>
[DEBUG  ] [App         ] kv <./my.kv> not found
[INFO   ] [Window      ] Provider: pygame
[ERROR  ] [WinPygame   ] unable to set icon
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/site-packages/kivy/core/window/window_pygame.py", line 179, in set_icon
    im = pygame.image.load(filename)
error: File is not a Windows BMP file
[DEBUG  ] [Window      ] Display driver Quartz
[DEBUG  ] [Window      ] Actual window size: 800x600
[DEBUG  ] [Window      ] Actual color bits r8 g8 b8 a8
[DEBUG  ] [Window      ] Actual depth bits: 24
[DEBUG  ] [Window      ] Actual stencil bits: 8
[DEBUG  ] [Window      ] Actual multisampling samples: 4
[INFO   ] [GL          ] OpenGL version <2.1 INTEL-8.10.44>
[INFO   ] [GL          ] OpenGL vendor <Intel Inc.>
[INFO   ] [GL          ] OpenGL renderer <Intel HD Graphics 4000 OpenGL Engine>
[INFO   ] [GL          ] OpenGL parsed version: 2, 1
[INFO   ] [GL          ] Shading version <1.20>
[INFO   ] [GL          ] Texture max size <16384>
[INFO   ] [GL          ] Texture max units <16>
[DEBUG  ] [Shader      ] Fragment compiled successfully
[DEBUG  ] [Shader      ] Vertex compiled successfully
[DEBUG  ] [ImageImageIO] Load </usr/local/lib/python2.7/site-packages/kivy/data/glsl/default.png>
[INFO   ] [GL          ] BGRA texture support is available
[INFO   ] [Window      ] virtual keyboard not allowed, single mode, not docked
[INFO   ] [OSC         ] using <multiprocessing> for socket
[DEBUG  ] [Base        ] Create provider from mouse
[INFO   ] [Base        ] Start application main loop
[INFO   ] [Base        ] Leaving application in progress...
 Traceback (most recent call last):
   File "demo.py", line 12, in <module>
     MyApp().run()
   File "/usr/local/lib/python2.7/site-packages/kivy/app.py", line 546, in run
     runTouchApp()
   File "/usr/local/lib/python2.7/site-packages/kivy/base.py", line 445, in runTouchApp
     EventLoop.window.mainloop()
   File "/usr/local/lib/python2.7/site-packages/kivy/core/window/window_pygame.py", line 324, in mainloop
     self._mainloop()
   File "/usr/local/lib/python2.7/site-packages/kivy/core/window/window_pygame.py", line 230, in _mainloop
     EventLoop.idle()
   File "/usr/local/lib/python2.7/site-packages/kivy/base.py", line 293, in idle
     Clock.tick()
   File "/usr/local/lib/python2.7/site-packages/kivy/clock.py", line 313, in tick
     self._process_events()
   File "/usr/local/lib/python2.7/site-packages/kivy/clock.py", line 424, in _process_events
     if event.tick(self._last_tick) is False:
   File "/usr/local/lib/python2.7/site-packages/kivy/clock.py", line 232, in tick
     ret = callback(self._dt)
   File "/usr/local/lib/python2.7/site-packages/kivy/uix/label.py", line 188, in texture_update
     self._label.refresh()
   File "/usr/local/lib/python2.7/site-packages/kivy/core/text/__init__.py", line 431, in refresh
     self.render(real=True)
   File "/usr/local/lib/python2.7/site-packages/kivy/core/text/markup.py", line 111, in render
     ret = self._real_render()
   File "/usr/local/lib/python2.7/site-packages/kivy/core/text/markup.py", line 408, in _real_render
     self.texture.blit_data(data)
 AttributeError: 'NoneType' object has no attribute 'blit_data'