<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"> 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>[ x] 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" checked=""> 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" checked=""> 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>: 4.4.6 (cliffs)</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="can't disclose that"><pre class="notranslate"><code class="notranslate">can't disclose that
</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>: Python 3.8.5</li>
<li><strong>Minimal Celery Version</strong>: 4.4.6 (cliffs)</li>
<li><strong>Minimal Kombu Version</strong>: 4.6.11</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="alembic==1.4.3
amqp==2.6.1
apache-airflow==1.10.12
apispec==1.3.3
appdirs==1.4.4
argcomplete==1.12.0
asgiref==3.2.10
astroid==2.4.2
attrs==19.3.0
Babel==2.8.0
billiard==3.6.3.0
cached-property==1.5.1
cachetools==4.1.1
cattrs==1.0.0
celery==4.4.6
certifi==2020.6.20
cffi==1.14.2
chardet==3.0.4
click==7.1.2
colorama==0.4.3
colorlog==4.0.2
configparser==3.5.3
coreapi==2.3.3
coreschema==0.0.4
croniter==0.3.34
cryptography==3.1
dataclasses==0.6
defusedxml==0.7.0rc1
dill==0.3.2
distlib==0.3.1
Django==3.0.5
django-braces==1.14.0
django-celery-beat==2.0.0
django-celery-results==1.2.1
django-cors-headers==3.5.0
django-debug-toolbar==2.2
django-extensions==3.0.9
django-oauth-toolkit==1.3.2
django-rest-framework-social-oauth2==1.1.0
django-rest-swagger==2.2.0
django-tenant-schemas==1.10.0
django-timezone-field==4.0
djangorestframework==3.11.1
djangorestframework-csv==2.1.0
djongo==1.3.3
dnspython==1.16.0
docutils==0.16
email-validator==1.1.1
eventlet==0.29.0
filelock==3.0.12
Flask==1.1.2
Flask-Admin==1.5.4
Flask-AppBuilder==2.3.4
Flask-Babel==1.0.0
Flask-Caching==1.3.3
Flask-JWT-Extended==3.24.1
Flask-Login==0.4.1
Flask-OpenID==1.2.5
Flask-SQLAlchemy==2.4.4
flask-swagger==0.2.14
Flask-WTF==0.14.3
funcsigs==1.0.2
future==0.18.2
gevent==20.6.2
google-api-core==1.22.2
google-api-python-client==1.11.0
google-auth==1.21.1
google-auth-httplib2==0.0.4
google-auth-oauthlib==0.4.1
google-cloud-core==1.4.1
google-cloud-logging==1.15.1
google-cloud-tasks==2.0.0
googleapis-common-protos==1.52.0
graphviz==0.14.1
greenlet==0.4.16
grpc-google-iam-v1==0.12.3
grpcio==1.32.0
gunicorn==20.0.4
httplib2==0.18.1
hvac==0.10.5
idna==2.10
iso8601==0.1.13
isort==5.5.2
itsdangerous==1.1.0
itypes==1.2.0
Jinja2==2.11.2
json-merge-patch==0.2
jsonschema==3.2.0
kombu==4.6.11
lazy-object-proxy==1.4.3
libcst==0.3.10
lockfile==0.12.2
Mako==1.1.3
Markdown==2.6.11
MarkupSafe==1.1.1
marshmallow==2.21.0
marshmallow-enum==1.5.1
marshmallow-sqlalchemy==0.23.1
mccabe==0.6.1
monotonic==1.5
mypy-extensions==0.4.3
mysqlclient==2.0.1
natsort==7.0.1
numpy==1.19.2
oauthlib==3.1.0
openapi-codec==1.3.2
ordered-set==4.0.2
pandas==1.1.2
pbr==5.5.0
pendulum==1.4.4
prison==0.1.3
proto-plus==1.9.1
protobuf==3.13.0
psutil==5.7.2
psycopg2==2.8.6
psycopg2-binary==2.8.6
pyasn1==0.4.8
pyasn1-modules==0.2.8
pycparser==2.20
pydot==1.4.1
Pygments==2.7.1
pygraphviz==1.6
PyJWT==1.7.1
pylint==2.6.0
pymongo==3.11.0
pyOpenSSL==19.1.0
pyparsing==2.4.7
pyrsistent==0.17.3
python-crontab==2.5.1
python-daemon==2.2.4
python-dateutil==2.8.1
python-editor==1.0.4
python-nvd3==0.15.0
python-slugify==4.0.1
python3-openid==3.2.0
pytz==2020.1
pytzdata==2020.1
PyYAML==5.3.1
redis==3.5.3
requests==2.24.0
requests-oauthlib==1.3.0
rsa==4.6
scout-apm==2.16.1
sentry-sdk==0.17.4
setproctitle==1.1.10
simplejson==3.17.2
six==1.15.0
social-auth-app-django==3.4.0
social-auth-core==3.3.3
SQLAlchemy==1.3.19
SQLAlchemy-JSONField==0.9.0
SQLAlchemy-Utils==0.36.8
sqlparse==0.2.4
stevedore==3.2.1
tabulate==0.8.7
tenacity==4.12.0
text-unidecode==1.3
thrift==0.13.0
toml==0.10.1
typing-extensions==3.7.4.3
typing-inspect==0.6.0
tzlocal==1.5.1
unicodecsv==0.14.1
uritemplate==3.0.1
urllib3==1.25.10
vine==1.3.0
virtualenv==20.0.31
virtualenv-clone==0.5.4
virtualenvwrapper==4.8.4
Werkzeug==0.16.1
wrapt==1.12.1
WTForms==2.3.3
zope.deprecation==4.4.0
zope.event==4.4
zope.interface==5.1.0"><pre class="notranslate"><code class="notranslate">alembic==1.4.3
amqp==2.6.1
apache-airflow==1.10.12
apispec==1.3.3
appdirs==1.4.4
argcomplete==1.12.0
asgiref==3.2.10
astroid==2.4.2
attrs==19.3.0
Babel==2.8.0
billiard==3.6.3.0
cached-property==1.5.1
cachetools==4.1.1
cattrs==1.0.0
celery==4.4.6
certifi==2020.6.20
cffi==1.14.2
chardet==3.0.4
click==7.1.2
colorama==0.4.3
colorlog==4.0.2
configparser==3.5.3
coreapi==2.3.3
coreschema==0.0.4
croniter==0.3.34
cryptography==3.1
dataclasses==0.6
defusedxml==0.7.0rc1
dill==0.3.2
distlib==0.3.1
Django==3.0.5
django-braces==1.14.0
django-celery-beat==2.0.0
django-celery-results==1.2.1
django-cors-headers==3.5.0
django-debug-toolbar==2.2
django-extensions==3.0.9
django-oauth-toolkit==1.3.2
django-rest-framework-social-oauth2==1.1.0
django-rest-swagger==2.2.0
django-tenant-schemas==1.10.0
django-timezone-field==4.0
djangorestframework==3.11.1
djangorestframework-csv==2.1.0
djongo==1.3.3
dnspython==1.16.0
docutils==0.16
email-validator==1.1.1
eventlet==0.29.0
filelock==3.0.12
Flask==1.1.2
Flask-Admin==1.5.4
Flask-AppBuilder==2.3.4
Flask-Babel==1.0.0
Flask-Caching==1.3.3
Flask-JWT-Extended==3.24.1
Flask-Login==0.4.1
Flask-OpenID==1.2.5
Flask-SQLAlchemy==2.4.4
flask-swagger==0.2.14
Flask-WTF==0.14.3
funcsigs==1.0.2
future==0.18.2
gevent==20.6.2
google-api-core==1.22.2
google-api-python-client==1.11.0
google-auth==1.21.1
google-auth-httplib2==0.0.4
google-auth-oauthlib==0.4.1
google-cloud-core==1.4.1
google-cloud-logging==1.15.1
google-cloud-tasks==2.0.0
googleapis-common-protos==1.52.0
graphviz==0.14.1
greenlet==0.4.16
grpc-google-iam-v1==0.12.3
grpcio==1.32.0
gunicorn==20.0.4
httplib2==0.18.1
hvac==0.10.5
idna==2.10
iso8601==0.1.13
isort==5.5.2
itsdangerous==1.1.0
itypes==1.2.0
Jinja2==2.11.2
json-merge-patch==0.2
jsonschema==3.2.0
kombu==4.6.11
lazy-object-proxy==1.4.3
libcst==0.3.10
lockfile==0.12.2
Mako==1.1.3
Markdown==2.6.11
MarkupSafe==1.1.1
marshmallow==2.21.0
marshmallow-enum==1.5.1
marshmallow-sqlalchemy==0.23.1
mccabe==0.6.1
monotonic==1.5
mypy-extensions==0.4.3
mysqlclient==2.0.1
natsort==7.0.1
numpy==1.19.2
oauthlib==3.1.0
openapi-codec==1.3.2
ordered-set==4.0.2
pandas==1.1.2
pbr==5.5.0
pendulum==1.4.4
prison==0.1.3
proto-plus==1.9.1
protobuf==3.13.0
psutil==5.7.2
psycopg2==2.8.6
psycopg2-binary==2.8.6
pyasn1==0.4.8
pyasn1-modules==0.2.8
pycparser==2.20
pydot==1.4.1
Pygments==2.7.1
pygraphviz==1.6
PyJWT==1.7.1
pylint==2.6.0
pymongo==3.11.0
pyOpenSSL==19.1.0
pyparsing==2.4.7
pyrsistent==0.17.3
python-crontab==2.5.1
python-daemon==2.2.4
python-dateutil==2.8.1
python-editor==1.0.4
python-nvd3==0.15.0
python-slugify==4.0.1
python3-openid==3.2.0
pytz==2020.1
pytzdata==2020.1
PyYAML==5.3.1
redis==3.5.3
requests==2.24.0
requests-oauthlib==1.3.0
rsa==4.6
scout-apm==2.16.1
sentry-sdk==0.17.4
setproctitle==1.1.10
simplejson==3.17.2
six==1.15.0
social-auth-app-django==3.4.0
social-auth-core==3.3.3
SQLAlchemy==1.3.19
SQLAlchemy-JSONField==0.9.0
SQLAlchemy-Utils==0.36.8
sqlparse==0.2.4
stevedore==3.2.1
tabulate==0.8.7
tenacity==4.12.0
text-unidecode==1.3
thrift==0.13.0
toml==0.10.1
typing-extensions==3.7.4.3
typing-inspect==0.6.0
tzlocal==1.5.1
unicodecsv==0.14.1
uritemplate==3.0.1
urllib3==1.25.10
vine==1.3.0
virtualenv==20.0.31
virtualenv-clone==0.5.4
virtualenvwrapper==4.8.4
Werkzeug==0.16.1
wrapt==1.12.1
WTForms==2.3.3
zope.deprecation==4.4.0
zope.event==4.4
zope.interface==5.1.0
</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>

<p dir="auto">Celery task is executed successfully</p>
<h1 dir="auto">Actual Behavior</h1>

<p dir="auto">Fails with TypeError:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="Task celery.backend_cleanup[75aa0973-534f-4812-a992-1ead4086f58c] raised unexpected: TypeError('unsupported type for timedelta seconds component: NoneType')
Traceback (most recent call last):
  File &quot;/usr/local/lib/python3.9/site-packages/kombu/utils/objects.py&quot;, line 42, in __get__
    return obj.__dict__[self.__name__]
KeyError: 'expires_delta'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File &quot;/usr/local/lib/python3.9/site-packages/celery/app/trace.py&quot;, line 412, in trace_task
    R = retval = fun(*args, **kwargs)
  File &quot;/usr/local/lib/python3.9/site-packages/celery/app/trace.py&quot;, line 704, in __protected_call__
    return self.run(*args, **kwargs)
  File &quot;/usr/local/lib/python3.9/site-packages/celery/app/builtins.py&quot;, line 25, in backend_cleanup
    app.backend.cleanup()
  File &quot;/usr/local/lib/python3.9/site-packages/celery/backends/mongodb.py&quot;, line 258, in cleanup
    {'date_done': {'$lt': self.app.now() - self.expires_delta}},
  File &quot;/usr/local/lib/python3.9/site-packages/kombu/utils/objects.py&quot;, line 44, in __get__
    value = obj.__dict__[self.__name__] = self.__get(obj)
  File &quot;/usr/local/lib/python3.9/site-packages/celery/backends/mongodb.py&quot;, line 312, in expires_delta
    return timedelta(seconds=self.expires)
TypeError: unsupported type for timedelta seconds component: NoneType"><pre class="notranslate"><code class="notranslate">Task celery.backend_cleanup[75aa0973-534f-4812-a992-1ead4086f58c] raised unexpected: TypeError('unsupported type for timedelta seconds component: NoneType')
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/kombu/utils/objects.py", line 42, in __get__
    return obj.__dict__[self.__name__]
KeyError: 'expires_delta'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/celery/app/trace.py", line 412, in trace_task
    R = retval = fun(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/celery/app/trace.py", line 704, in __protected_call__
    return self.run(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/celery/app/builtins.py", line 25, in backend_cleanup
    app.backend.cleanup()
  File "/usr/local/lib/python3.9/site-packages/celery/backends/mongodb.py", line 258, in cleanup
    {'date_done': {'$lt': self.app.now() - self.expires_delta}},
  File "/usr/local/lib/python3.9/site-packages/kombu/utils/objects.py", line 44, in __get__
    value = obj.__dict__[self.__name__] = self.__get(obj)
  File "/usr/local/lib/python3.9/site-packages/celery/backends/mongodb.py", line 312, in expires_delta
    return timedelta(seconds=self.expires)
TypeError: unsupported type for timedelta seconds component: NoneType
</code></pre></div>
<p dir="auto">In the <a href="http://docs.celeryproject.org/en/latest/userguide/canvas.html#the-primitives" rel="nofollow">Documentations</a> says:</p>
<blockquote>
<p dir="auto">Groups and chords accepts partial arguments too, so in a chain the return value of the previous task is forwarded to all tasks in the group...</p>
</blockquote>
<p dir="auto">but it doesn't if group contain chain.</p>
<p dir="auto"><strong>Steps to reproduce</strong></p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="# ct.py
from __future__ import absolute_import, unicode_literals
from celery import Celery

app = Celery(
    'ct',
    broker='amqp://guest@localhost//',
    backend='cache+memcached://127.0.0.1:11211/'
)

@app.task
def inc(x):
   x += 1
   return x

@app.task
def nothing(x):
   return x

if __name__ == '__main__':
    app.start()"><pre class="notranslate"><code class="notranslate"># ct.py
from __future__ import absolute_import, unicode_literals
from celery import Celery

app = Celery(
    'ct',
    broker='amqp://guest@localhost//',
    backend='cache+memcached://127.0.0.1:11211/'
)

@app.task
def inc(x):
   x += 1
   return x

@app.task
def nothing(x):
   return x

if __name__ == '__main__':
    app.start()
</code></pre></div>
<p dir="auto">Start worker:<br>
<code class="notranslate">python ct.py worker -l info</code></p>
<p dir="auto">In python console:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="&gt;&gt;&gt; from ct import inc, nothing
&gt;&gt;&gt; from celery import group, chain
&gt;&gt;&gt; t = chain(inc.s(),group(chain(nothing.s(), inc.s()), inc.s()))
&gt;&gt;&gt; r = t.delay(0)
&gt;&gt;&gt; "><pre class="notranslate"><code class="notranslate">&gt;&gt;&gt; from ct import inc, nothing
&gt;&gt;&gt; from celery import group, chain
&gt;&gt;&gt; t = chain(inc.s(),group(chain(nothing.s(), inc.s()), inc.s()))
&gt;&gt;&gt; r = t.delay(0)
&gt;&gt;&gt; 
</code></pre></div>
<p dir="auto">In <code class="notranslate">celery</code> log:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="[2017-04-10 12:43:36,126: INFO/MainProcess] Received task: ct.inc[5c1beeff-d785-4d81-af2c-35a5bba839ab]  
[2017-04-10 12:43:37,257: WARNING/PoolWorker-1] /home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/app/trace.py:542: RuntimeWarning: Exception raised outside body: TypeError('nothing() takes exactly 1 argument (0 given)',):
Traceback (most recent call last):
  File &quot;/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/app/trace.py&quot;, line 424, in trace_task
    parent_id=uuid, root_id=root_id,
  File &quot;/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py&quot;, line 987, in apply_async
    args=args, kwargs=kwargs, **options))
  File &quot;/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py&quot;, line 1063, in _apply_tasks
    **options)
  File &quot;/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py&quot;, line 567, in apply_async
    dict(self.options, **options) if options else self.options))
  File &quot;/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py&quot;, line 597, in run
    first_task.apply_async(**options)
  File &quot;/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py&quot;, line 221, in apply_async
    return _apply(args, kwargs, **options)
  File &quot;/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/app/task.py&quot;, line 518, in apply_async
    check_arguments(*(args or ()), **(kwargs or {}))
TypeError: nothing() takes exactly 1 argument (0 given)

  exc, exc_info.traceback)))
[2017-04-10 12:43:37,262: ERROR/PoolWorker-1] Task ct.inc[5c1beeff-d785-4d81-af2c-35a5bba839ab] raised unexpected: TypeError('nothing() takes exactly 1 argument (0 given)',)
Traceback (most recent call last):
  File &quot;/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/app/trace.py&quot;, line 424, in trace_task
    parent_id=uuid, root_id=root_id,
  File &quot;/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py&quot;, line 987, in apply_async
    args=args, kwargs=kwargs, **options))
  File &quot;/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py&quot;, line 1063, in _apply_tasks
    **options)
  File &quot;/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py&quot;, line 567, in apply_async
    dict(self.options, **options) if options else self.options))
  File &quot;/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py&quot;, line 597, in run
    first_task.apply_async(**options)
  File &quot;/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py&quot;, line 221, in apply_async
    return _apply(args, kwargs, **options)
  File &quot;/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/app/task.py&quot;, line 518, in apply_async
    check_arguments(*(args or ()), **(kwargs or {}))
TypeError: nothing() takes exactly 1 argument (0 given)"><pre class="notranslate"><code class="notranslate">[2017-04-10 12:43:36,126: INFO/MainProcess] Received task: ct.inc[5c1beeff-d785-4d81-af2c-35a5bba839ab]  
[2017-04-10 12:43:37,257: WARNING/PoolWorker-1] /home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/app/trace.py:542: RuntimeWarning: Exception raised outside body: TypeError('nothing() takes exactly 1 argument (0 given)',):
Traceback (most recent call last):
  File "/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/app/trace.py", line 424, in trace_task
    parent_id=uuid, root_id=root_id,
  File "/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py", line 987, in apply_async
    args=args, kwargs=kwargs, **options))
  File "/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py", line 1063, in _apply_tasks
    **options)
  File "/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py", line 567, in apply_async
    dict(self.options, **options) if options else self.options))
  File "/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py", line 597, in run
    first_task.apply_async(**options)
  File "/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py", line 221, in apply_async
    return _apply(args, kwargs, **options)
  File "/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/app/task.py", line 518, in apply_async
    check_arguments(*(args or ()), **(kwargs or {}))
TypeError: nothing() takes exactly 1 argument (0 given)

  exc, exc_info.traceback)))
[2017-04-10 12:43:37,262: ERROR/PoolWorker-1] Task ct.inc[5c1beeff-d785-4d81-af2c-35a5bba839ab] raised unexpected: TypeError('nothing() takes exactly 1 argument (0 given)',)
Traceback (most recent call last):
  File "/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/app/trace.py", line 424, in trace_task
    parent_id=uuid, root_id=root_id,
  File "/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py", line 987, in apply_async
    args=args, kwargs=kwargs, **options))
  File "/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py", line 1063, in _apply_tasks
    **options)
  File "/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py", line 567, in apply_async
    dict(self.options, **options) if options else self.options))
  File "/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py", line 597, in run
    first_task.apply_async(**options)
  File "/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/canvas.py", line 221, in apply_async
    return _apply(args, kwargs, **options)
  File "/home/vagrant/ct-env/local/lib/python2.7/site-packages/celery/app/task.py", line 518, in apply_async
    check_arguments(*(args or ()), **(kwargs or {}))
TypeError: nothing() takes exactly 1 argument (0 given)
</code></pre></div>
<p dir="auto"><strong>Expecting result</strong></p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="&gt;&gt;&gt; r.get()
[2, 2]"><pre class="notranslate"><code class="notranslate">&gt;&gt;&gt; r.get()
[2, 2]
</code></pre></div>
<p dir="auto"><strong>Celery info</strong></p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="celery -A ct report

software -&gt; celery:4.0.2 (latentcall) kombu:4.0.2 py:2.7.9
            billiard:3.5.0.2 py-amqp:2.1.4
platform -&gt; system:Linux arch:64bit, ELF imp:CPython
loader   -&gt; celery.loaders.app.AppLoader
settings -&gt; transport:amqp results:cache+memcached://127.0.0.1:11211/

broker_url: u'amqp://guest:********@localhost:5672//'
result_backend: u'cache+memcached://127.0.0.1:11211/'
"><pre class="notranslate"><code class="notranslate">celery -A ct report

software -&gt; celery:4.0.2 (latentcall) kombu:4.0.2 py:2.7.9
            billiard:3.5.0.2 py-amqp:2.1.4
platform -&gt; system:Linux arch:64bit, ELF imp:CPython
loader   -&gt; celery.loaders.app.AppLoader
settings -&gt; transport:amqp results:cache+memcached://127.0.0.1:11211/

broker_url: u'amqp://guest:********@localhost:5672//'
result_backend: u'cache+memcached://127.0.0.1:11211/'

</code></pre></div>
<p dir="auto"><strong>Notes</strong></p>
<p dir="auto">Work fine with Celery 3.x</p>