Looks like logs are crashing my Django app

Looks like logs are crashing my Django app

I have a Django app running on heroku. The app keeps crashing with the
following stacktrace:
Traceback (most recent call last):
File "/app/.heroku/python/bin/honcho", line 9, in <module>
load_entry_point('honcho==0.4.2', 'console_scripts', 'honcho')()
File "/app/.heroku/python/lib/python2.7/site-packages/honcho/command.py",
line 292, in main
app.parse()
File "/app/.heroku/python/lib/python2.7/site-packages/honcho/command.py",
line 129, in parse
options.func(self, options)
File "/app/.heroku/python/lib/python2.7/site-packages/honcho/command.py",
line 190, in start
sys.exit(process_manager.loop())
File "/app/.heroku/python/lib/python2.7/site-packages/honcho/process.py",
line 114, in loop
File "/app/.heroku/python/lib/python2.7/site-packages/honcho/printer.py",
line 22, in write
Process exited with status 1
From Honcho's printer.py source code it looks like someting is going wrong
while honcho is trying to write to the console.
My app is pulling data from web pages so I may print some text with
accented characters. Is that related ?
Currently i'm printing things like this:
logger.info('Saved article' + str(title) + '.')
I may also dump some json from time to time:
logger.debug('Article: %s' % json.dumps(article_datas, indent=4))
It is working fine on my development machine but not on Heroku. Do I need
to log things differently ? Why is this not working on Heroku ?