ModuleNotFoundError: No module named 'demo'

I’m trying deploying a Django app “news” from W. S. Vincent’s book (the last 16th chapter). But every time i face this error:

[info][2022-12-20 10:44:41 +0000] [525] [ERROR] Exception in worker process
[info]Traceback (most recent call last):
[info]  File "/usr/local/lib/python3.10/site-packages/gunicorn/arbiter.py", line 589, in spawn_worker
[info]    worker.init_process()
[info]  File "/usr/local/lib/python3.10/site-packages/gunicorn/workers/base.py", line 134, in init_process
[info]    self.load_wsgi()
[info]  File "/usr/local/lib/python3.10/site-packages/gunicorn/workers/base.py", line 146, in load_wsgi
[info]    self.wsgi = self.app.wsgi()
[info]  File "/usr/local/lib/python3.10/site-packages/gunicorn/app/base.py", line 67, in wsgi
[info]    self.callable = self.load()
[info]  File "/usr/local/lib/python3.10/site-packages/gunicorn/app/wsgiapp.py", line 58, in load
[info]    return self.load_wsgiapp()
[info]  File "/usr/local/lib/python3.10/site-packages/gunicorn/app/wsgiapp.py", line 48, in load_wsgiapp
[info]    return util.import_app(self.app_uri)
[info]  File "/usr/local/lib/python3.10/site-packages/gunicorn/util.py", line 359, in import_app
[info]    mod = importlib.import_module(module)
[info]  File "/usr/local/lib/python3.10/importlib/__init__.py", line 126, in import_module
[info]    return _bootstrap._gcd_import(name[level:], package, level)
[info]  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
[info]  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
[info]  File "<frozen importlib._bootstrap>", line 992, in _find_and_load_unlocked
[info]  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
[info]  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
[info]  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
[info]  File "<frozen importlib._bootstrap>", line 1004, in _find_and_load_unlocked
[info]ModuleNotFoundError: No module named 'demo'
[info][2022-12-20 10:44:41 +0000] [525] [INFO] Worker exiting (pid: 525)
[info][2022-12-20 10:44:41 +0000] [520] [INFO] Shutting down: Master
[info][2022-12-20 10:44:41 +0000] [520] [INFO] Reason: Worker failed to boot.
[info]Starting clean up.
--> v0 failed - Failed due to unhealthy allocations - no stable job version to auto revert to and deploying as v1

I tried deleting Procfile. Also tried changing its content from “web: gunicorn django_project.wsgi --log-file -” to “web: gunicorn django_project:app”. But the problem persists

Ok. It is actually required to replace "demo.wsgi" with your Django project’s name in the Dockerfile. No Procfile required