Comment 11 for bug 1562734

Thank you both. There's no obvious error or traceback in the logs. I'd still like to see Asvin's x-0-greeter.log, but at the moment it doesn't look like Onboard crashes outright. Actually, there's little hint it is being started at all, but this seems to be the normal case.

There is an undocumented (read awkward) way to get a log file from Onboard, even when running in unity-greeter (which hard-codes Onboard's command-line). That would be good to have.

Make /usr/lib/python3/dist-packages/Onboard/Config.py starting from line 290 look like this:
         # optionally log to file; everything, including stack traces
         if 1:
             options.debug = "debug"
             logfile = open("/tmp/onboard.log", "w")
             #sys.stdout = logfile
             sys.stderr = logfile

Edit it by hand or use this one-liner:
sudo vi /usr/lib/python3/dist-packages/Onboard/Config.py +"%s/if 0/if 1/" +"%s/sys.stdout = logfile/#sys.stdout = logfile/" +wq

Then reboot, make sure the black rectangle is still visible at the login screen (i.e. the keyboard is still enabled), login and post the file "/tmp/onboard.log" here. Note that Onboard will probably fail to start in the user session now, until you delete /tmp/onboard.log.

When done, undo the changes with:
sudo apt-get install --reinstall onboard