django-crispy-forms is present in requirements.txt (added using pip freeze > requirements.txt) requirements.txt
asgiref==3.2.10
autopep8==1.5.4
beautifulsoup4==4.9.1
certifi==2020.6.20
chardet==3.0.4
Django==3.1
django-crispy-forms==1.9.2
feedparser==5.2.1
idna==2.10
Pillow==7.2.0
pycodestyle==2.6.0
python-dateutil==2.8.1
pytz==2020.1
requests==2.24.0
six==1.15.0
soupsieve==2.0.1
sqlparse==0.3.1
toml==0.10.1
urllib3==1.25.10
heroku run pip freeze
appdirs==1.4.4
asgiref==3.2.10
certifi==2020.6.20
distlib==0.3.1
Django==3.1.1
filelock==3.0.12
gunicorn==20.0.4
pipenv==2018.5.18
pytz==2020.1
six==1.15.0
sqlparse==0.3.1
virtualenv==20.0.31
virtualenv-clone==0.5.4
whitenoise==5.2.0
So, this leads to Application Error on heroku deploy and the heroku logs --tail
gives ModuleNotFoundError: No module named 'crispy_forms'