Issue 1:
Checklist

I have checked the issues list

for similar or identical bug reports.

I have checked the pull requests list

for existing proposed fixes.

I have checked the commit log

to find out if the bug was already fixed in the master branch.

I have included all related issues and possible duplicate issues in this issue

(If there are none, check this box anyway).

Related Issues and Possible Duplicates

Related Issues

None

Possible Duplicates

None

Description

The documentation page (https://pypi.org/project/celery/) has four broken links to webpages/documents. All links are to pages/documents that are no longer there. 404 errors are returned:

Web link at the top of the page

Get Started section:

First Steps with Celery

Next Steps

Documentation Section:

Latest Documentation

Suggestions

Please fix those links so that both documents render as expected. As a developer completely new to Celery these missing documents leave quite a gap. Thanks in advance for your support and maintaining this library. I look forward to learning what Celery can do and making the most of it.

Issue 2:
This doesn't happen on 4.4.3, only on 4.4.4.

Here is a traceback:

Traceback (most recent call last):
File "/usr/local/lib/python3.7/site-packages/kombu/utils/objects.py", line 42, in __get__
return obj.__dict__[self.__name__]
KeyError: 'backend'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "<stdin>", line 2, in <module>
File "/usr/local/lib/python3.7/site-packages/celery/app/task.py", line 569, in apply_async
**options
File "/usr/local/lib/python3.7/site-packages/celery/app/base.py", line 779, in send_task
self.backend.on_task_call(P, task_id)
File "/usr/local/lib/python3.7/site-packages/kombu/utils/objects.py", line 44, in __get__
value = obj.__dict__[self.__name__] = self.__get(obj)
File "/usr/local/lib/python3.7/site-packages/celery/app/base.py", line 1232, in backend
return self._get_backend()
File "/usr/local/lib/python3.7/site-packages/celery/app/base.py", line 949, in _get_backend
self.loader)
File "/usr/local/lib/python3.7/site-packages/celery/app/backends.py", line 74, in by_url
return by_name(backend, loader), url
File "/usr/local/lib/python3.7/site-packages/celery/app/backends.py", line 54, in by_name
cls = symbol_by_name(backend, aliases)
File "/usr/local/lib/python3.7/site-packages/kombu/utils/imports.py", line 57, in symbol_by_name
module = imp(module_name, package=package, **kwargs)
File "/usr/local/lib/python3.7/importlib/__init__.py", line 127, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
File "<frozen importlib._bootstrap>", line 983, in _find_and_load
File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 728, in exec_module
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "/usr/local/lib/python3.7/site-packages/celery/backends/base.py", line 10, in <module>
from future.utils import raise_with_traceback
ModuleNotFoundError: No module named 'future'

I'm running Python 3.7.4 on Debian v9.

root@6b09806573e5:/app# cat /etc/*release*
PRETTY_NAME="Debian GNU/Linux 9 (stretch)"
NAME="Debian GNU/Linux"
VERSION_ID="9"
VERSION="9 (stretch)"
VERSION_CODENAME=stretch
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"

root@6b09806573e5:/app# python --version
Python 3.7.4

Checklist

I have verified that the issue exists against the master branch of Celery.

This has already been asked to the discussion group first.

I have read the relevant section in the

contribution guide

on reporting bugs.

I have checked the issues list

for similar or identical bug reports.

I have checked the pull requests list

for existing proposed fixes.

I have checked the commit log

to find out if the bug was already fixed in the master branch.

I have included all related issues and possible duplicate issues

in this issue (If there are none, check this box anyway).

Mandatory Debugging Information

I have included the output of celery -A proj report in the issue.

(if you are not able to do this, then at least specify the Celery

version affected).

I have verified that the issue exists against the master branch of Celery.

I have included the contents of pip freeze in the issue.

I have included all the versions of all the external dependencies required

to reproduce this bug.

Optional Debugging Information

I have tried reproducing the issue on more than one Python version

and/or implementation.

I have tried reproducing the issue on more than one message broker and/or

result backend.

I have tried reproducing the issue on more than one version of the message

broker and/or result backend.

I have tried reproducing the issue on more than one operating system.

I have tried reproducing the issue on more than one workers pool.

I have tried reproducing the issue with autoscaling, retries,

ETA/Countdown & rate limits disabled.

I have tried reproducing the issue after downgrading

and/or upgrading Celery and its dependencies.

Related Issues and Possible Duplicates

Related Issues

None

Possible Duplicates

None

Environment & Settings

Celery version:

celery report Output:

Steps to Reproduce

Required Dependencies

Minimal Python Version: N/A or Unknown

Minimal Celery Version: N/A or Unknown

Minimal Kombu Version: N/A or Unknown

Minimal Broker Version: N/A or Unknown

Minimal Result Backend Version: N/A or Unknown

Minimal OS and/or Kernel Version: N/A or Unknown

Minimal Broker Client Version: N/A or Unknown

Minimal Result Backend Client Version: N/A or Unknown

Python Packages

pip freeze Output:

root@6b09806573e5:/app# pip freeze
amqp==2.6.0
bcrypt==3.1.7
beautifulsoup4==4.7.1
billiard==3.6.3.0
bleach==3.1.0
blinker==1.4
celery==4.4.4
certifi==2020.4.5.1
cffi==1.14.0
chardet==3.0.4
Click==7.0
cryptography==2.9.2
CvLib==3.3.7
decorator==4.4.2
docker==4.1.0
Flask==1.1.1
Flask-APIBlueprint==1.0.0
Flask-Limiter==1.0.1
Flask-SQLAlchemy==2.3.2
flask-swagger==0.2.13
html5lib==1.0.1
idna==2.8
importlib-metadata==1.6.0
itsdangerous==1.1.0
Jinja2==2.10.1
kombu==4.6.10
limits==1.5.1
MarkupSafe==1.1.1
marshmallow==3.0.0b2
mysqlclient==1.4.6
paramiko==2.4.1
pbr==5.4.5
py==1.8.1
pyasn1==0.4.8
pycparser==2.20
pymssql==2.1.4
PyNaCl==1.4.0
python-dateutil==2.8.0
pytz==2017.2
PyYAML==5.3.1
requests==2.21.0
retry==0.9.2
six==1.15.0
soupsieve==2.0.1
SQLAlchemy==1.2.18
sshtunnel==0.1.5
urllib3==1.24.3
uWSGI==2.0.18
vine==1.3.0
webencodings==0.5.1
websocket-client==0.57.0
Werkzeug==0.16.0
zipp==3.1.0

Other Dependencies

N/A

Minimally Reproducible Test Case

Expected Behavior

Actual Behavior