<h1 dir="auto">Checklist</h1>

<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have checked the <a href="https://github.com/celery/celery/issues?utf8=%E2%9C%93&amp;q=is%3Aissue+label%3A%22Category%3A+Documentation%22+">issues list</a><br>
for similar or identical bug reports.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have checked the <a href="https://github.com/celery/celery/pulls?q=is%3Apr+label%3A%22Category%3A+Documentation%22">pull requests list</a><br>
for existing proposed fixes.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have checked the <a href="https://github.com/celery/celery/commits/master">commit log</a><br>
to find out if the bug was already fixed in the master branch.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have included all related issues and possible duplicate issues in this issue<br>
(If there are none, check this box anyway).</li>
</ul>
<h2 dir="auto">Related Issues and Possible Duplicates</h2>

<h4 dir="auto">Related Issues</h4>
<ul dir="auto">
<li>None</li>
</ul>
<h4 dir="auto">Possible Duplicates</h4>
<ul dir="auto">
<li>None</li>
</ul>
<h1 dir="auto">Description</h1>
<p dir="auto">The documentation page (<a href="https://pypi.org/project/celery/" rel="nofollow">https://pypi.org/project/celery/</a>) has four broken links to webpages/documents. All links are to pages/documents that are no longer there. 404 errors are returned:</p>
<ul dir="auto">
<li><a href="https://docs.celeryproject.org/en/stable/index.html" rel="nofollow">Web link at the top of the page</a><br>
Get Started section:</li>
<li><a href="http://docs.celeryproject.org/en/latest/getting-started/first-steps-with-celery.html" rel="nofollow">First Steps with Celery</a></li>
<li><a href="http://docs.celeryproject.org/en/latest/getting-started/next-steps.html" rel="nofollow">Next Steps</a><br>
Documentation Section:</li>
<li><a href="https://docs.celeryproject.org/en/latest/" rel="nofollow">Latest Documentation</a></li>
</ul>
<h1 dir="auto">Suggestions</h1>
<p dir="auto">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.</p>
<p dir="auto">This doesn't happen on 4.4.3, only on 4.4.4.</p>
<p dir="auto">Here is a traceback:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="Traceback (most recent call last):
  File &quot;/usr/local/lib/python3.7/site-packages/kombu/utils/objects.py&quot;, 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 &quot;&lt;stdin&gt;&quot;, line 2, in &lt;module&gt;
  File &quot;/usr/local/lib/python3.7/site-packages/celery/app/task.py&quot;, line 569, in apply_async
    **options
  File &quot;/usr/local/lib/python3.7/site-packages/celery/app/base.py&quot;, line 779, in send_task
    self.backend.on_task_call(P, task_id)
  File &quot;/usr/local/lib/python3.7/site-packages/kombu/utils/objects.py&quot;, line 44, in __get__
    value = obj.__dict__[self.__name__] = self.__get(obj)
  File &quot;/usr/local/lib/python3.7/site-packages/celery/app/base.py&quot;, line 1232, in backend
    return self._get_backend()
  File &quot;/usr/local/lib/python3.7/site-packages/celery/app/base.py&quot;, line 949, in _get_backend
    self.loader)
  File &quot;/usr/local/lib/python3.7/site-packages/celery/app/backends.py&quot;, line 74, in by_url
    return by_name(backend, loader), url
  File &quot;/usr/local/lib/python3.7/site-packages/celery/app/backends.py&quot;, line 54, in by_name
    cls = symbol_by_name(backend, aliases)
  File &quot;/usr/local/lib/python3.7/site-packages/kombu/utils/imports.py&quot;, line 57, in symbol_by_name
    module = imp(module_name, package=package, **kwargs)
  File &quot;/usr/local/lib/python3.7/importlib/__init__.py&quot;, line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File &quot;&lt;frozen importlib._bootstrap&gt;&quot;, line 1006, in _gcd_import
  File &quot;&lt;frozen importlib._bootstrap&gt;&quot;, line 983, in _find_and_load
  File &quot;&lt;frozen importlib._bootstrap&gt;&quot;, line 967, in _find_and_load_unlocked
  File &quot;&lt;frozen importlib._bootstrap&gt;&quot;, line 677, in _load_unlocked
  File &quot;&lt;frozen importlib._bootstrap_external&gt;&quot;, line 728, in exec_module
  File &quot;&lt;frozen importlib._bootstrap&gt;&quot;, line 219, in _call_with_frames_removed
  File &quot;/usr/local/lib/python3.7/site-packages/celery/backends/base.py&quot;, line 10, in &lt;module&gt;
    from future.utils import raise_with_traceback
ModuleNotFoundError: No module named 'future'"><pre class="notranslate"><code class="notranslate">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 "&lt;stdin&gt;", line 2, in &lt;module&gt;
  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 "&lt;frozen importlib._bootstrap&gt;", line 1006, in _gcd_import
  File "&lt;frozen importlib._bootstrap&gt;", line 983, in _find_and_load
  File "&lt;frozen importlib._bootstrap&gt;", line 967, in _find_and_load_unlocked
  File "&lt;frozen importlib._bootstrap&gt;", line 677, in _load_unlocked
  File "&lt;frozen importlib._bootstrap_external&gt;", line 728, in exec_module
  File "&lt;frozen importlib._bootstrap&gt;", line 219, in _call_with_frames_removed
  File "/usr/local/lib/python3.7/site-packages/celery/backends/base.py", line 10, in &lt;module&gt;
    from future.utils import raise_with_traceback
ModuleNotFoundError: No module named 'future'
</code></pre></div>
<p dir="auto">I'm running Python 3.7.4 on Debian v9.</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="root@6b09806573e5:/app# cat /etc/*release*
PRETTY_NAME=&quot;Debian GNU/Linux 9 (stretch)&quot;
NAME=&quot;Debian GNU/Linux&quot;
VERSION_ID=&quot;9&quot;
VERSION=&quot;9 (stretch)&quot;
VERSION_CODENAME=stretch
ID=debian
HOME_URL=&quot;https://www.debian.org/&quot;
SUPPORT_URL=&quot;https://www.debian.org/support&quot;
BUG_REPORT_URL=&quot;https://bugs.debian.org/&quot;

root@6b09806573e5:/app# python --version
Python 3.7.4
"><pre class="notranslate"><code class="notranslate">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

</code></pre></div>

<h1 dir="auto">Checklist</h1>

<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have verified that the issue exists against the <code class="notranslate">master</code> branch of Celery.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> This has already been asked to the <a href="https://groups.google.com/forum/#!forum/celery-users" rel="nofollow">discussion group</a> first.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have read the relevant section in the<br>
<a href="http://docs.celeryproject.org/en/latest/contributing.html#other-bugs" rel="nofollow">contribution guide</a><br>
on reporting bugs.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have checked the <a href="https://github.com/celery/celery/issues?q=is%3Aissue+label%3A%22Issue+Type%3A+Bug+Report%22+-label%3A%22Category%3A+Documentation%22">issues list</a><br>
for similar or identical bug reports.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have checked the <a href="https://github.com/celery/celery/pulls?q=is%3Apr+label%3A%22PR+Type%3A+Bugfix%22+-label%3A%22Category%3A+Documentation%22">pull requests list</a><br>
for existing proposed fixes.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have checked the <a href="https://github.com/celery/celery/commits/master">commit log</a><br>
to find out if the bug was already fixed in the master branch.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have included all related issues and possible duplicate issues<br>
in this issue (If there are none, check this box anyway).</li>
</ul>
<h2 dir="auto">Mandatory Debugging Information</h2>
<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have included the output of <code class="notranslate">celery -A proj report</code> in the issue.<br>
(if you are not able to do this, then at least specify the Celery<br>
version affected).</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have verified that the issue exists against the <code class="notranslate">master</code> branch of Celery.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have included the contents of <code class="notranslate">pip freeze</code> in the issue.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have included all the versions of all the external dependencies required<br>
to reproduce this bug.</li>
</ul>
<h2 dir="auto">Optional Debugging Information</h2>

<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue on more than one Python version<br>
and/or implementation.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue on more than one message broker and/or<br>
result backend.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue on more than one version of the message<br>
broker and/or result backend.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue on more than one operating system.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue on more than one workers pool.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue with autoscaling, retries,<br>
ETA/Countdown &amp; rate limits disabled.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue after downgrading<br>
and/or upgrading Celery and its dependencies.</li>
</ul>
<h2 dir="auto">Related Issues and Possible Duplicates</h2>

<h4 dir="auto">Related Issues</h4>
<ul dir="auto">
<li>None</li>
</ul>
<h4 dir="auto">Possible Duplicates</h4>
<ul dir="auto">
<li>None</li>
</ul>
<h2 dir="auto">Environment &amp; Settings</h2>

<p dir="auto"><strong>Celery version</strong>:</p>

<details>
<summary><b><code class="notranslate">celery report</code> Output:</b></summary>
<p dir="auto">
</p><div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content=""><pre class="notranslate"><code class="notranslate"></code></pre></div>
<p dir="auto"></p>
</details>
<h1 dir="auto">Steps to Reproduce</h1>
<h2 dir="auto">Required Dependencies</h2>

<ul dir="auto">
<li><strong>Minimal Python Version</strong>: N/A or Unknown</li>
<li><strong>Minimal Celery Version</strong>: N/A or Unknown</li>
<li><strong>Minimal Kombu Version</strong>: N/A or Unknown</li>
<li><strong>Minimal Broker Version</strong>: N/A or Unknown</li>
<li><strong>Minimal Result Backend Version</strong>: N/A or Unknown</li>
<li><strong>Minimal OS and/or Kernel Version</strong>: N/A or Unknown</li>
<li><strong>Minimal Broker Client Version</strong>: N/A or Unknown</li>
<li><strong>Minimal Result Backend Client Version</strong>: N/A or Unknown</li>
</ul>
<h3 dir="auto">Python Packages</h3>

<details>
<summary><b><code class="notranslate">pip freeze</code> Output:</b></summary>
<p dir="auto">
</p><div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="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"><pre class="notranslate"><code class="notranslate">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
</code></pre></div>
<p dir="auto"></p>
</details>
<h3 dir="auto">Other Dependencies</h3>

<details>
<p dir="auto">
N/A
</p>
</details>
<h2 dir="auto">Minimally Reproducible Test Case</h2>

<details>
<p dir="auto">
</p><div class="highlight highlight-source-python notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content=""><pre class="notranslate"></pre></div>
<p dir="auto"></p>
</details>
<h1 dir="auto">Expected Behavior</h1>

<h1 dir="auto">Actual Behavior</h1>