Django crontab not executing test function

Your code actually works. You may be think that print("Hello") should appear in stdout? So it doesn't work that way, because cron doesn't use stdour and stderr for it's output. To see actual results you should point path to some log file in CRONJOBS list: just put '>> /path/to/log/file.log' as last argument, e.g:

CRONJOBS = [
    ('*/1 * * * *', 'media_api_server.cron.cronSendEmail', '>> /path/to/log/file.log')
]

Also it might be helpful to redirect your errors to stdout too. For this you heed to add CRONTAB_COMMAND_SUFFIX = '2>&1' to your settings.py

source sometimes not working in shell scripts

use . (dot) instead

*/1 * * * * . /home/app/env/bin/activate e.t.c.