How to see details of Django errors with Gunicorn?

From your comment I think this is a config problem in your django site, not a matter of gunicorn log, logs will not show more than django send to it.

Here is an example of how you can configure django setting to send log to your file (instead of send it to admins by email as default):

LOGGING = {
    'version': 1,
    'disable_existing_loggers': True,
    'formatters': {
        'verbose': {
            'format': '%(asctime)s %(levelname)s [%(name)s:%(lineno)s] %(module)s %(process)d %(thread)d %(message)s'
        }
    },
    'handlers': {
        'gunicorn': {
            'level': 'DEBUG',
            'class': 'logging.handlers.RotatingFileHandler',
            'formatter': 'verbose',
            'filename': '/opt/djangoprojects/reports/bin/gunicorn.errors',
            'maxBytes': 1024 * 1024 * 100,  # 100 mb
        }
    },
    'loggers': {
        'gunicorn.errors': {
            'level': 'DEBUG',
            'handlers': ['gunicorn'],
            'propagate': True,
        },
    }
}

Read configuring logging (it provide a very well explanations of log settings options) and study the file django/utils/log.py to configure django loggin to appears more detailed on gunicorn logs.

Also check this answer and this which provide setting examples to send logs errors directly to a file. And consider to use Sentry to handle log errors, as is recomended by django guys.

Hope this helps.