No module named 'backports' after python upgrade

Open JanMalte opened this issue 2 years ago • 1 comments

We've upgraded the python version from 3.8 to 3.11. After the upgrade, the celery beat is not starting anymore.

When running celery --app app beat --loglevel WARNING the process crashes with the following error message: ModuleNotFoundError: No module named 'backports'

The same issue is reported/asked at stackoverflow (using python 3.10): https://stackoverflow.com/q/77416290/10992051

Environment & Settings

Celery version: 5.3.6 (emerald-rush)

celery report Output:

software -> celery:5.3.6 (emerald-rush) kombu:5.3.4 py:3.12.1
            billiard:4.2.0 py-amqp:5.2.0
platform -> system:Linux arch:64bit, ELF
            kernel version:5.4.0-167-generic imp:CPython
loader   -> celery.loaders.default.Loader
settings -> transport:amqp results:disabled

deprecated_settings: None

Steps to Reproduce

Required Dependencies

Minimal Python Version: 3.11.7
Minimal Celery Version: 5.3.6
Minimal Kombu Version: 5.3.4

Python Packages

pip freeze Output:

amqp==5.2.0
asgiref==3.7.2
asttokens==2.4.1
attrs==23.1.0
billiard==4.2.0
bleach==6.1.0
bx-py-utils==71
celery==5.3.6
certifi==2023.11.17
charset-normalizer==3.3.2
click==8.1.7
click-didyoumean==0.3.0
click-plugins==1.1.1
click-repl==0.3.0
colorhash==2.0.0
colorutils==0.3.0
decorator==5.1.1
deprecation==2.1.0
dict2xml==1.7.3
Django==4.1.13
django-appconf==1.0.6
django-extensions==3.2.3
django-redis==5.4.0
django-reversion==5.0.8
django-tools==0.54.0
djangorestframework==3.14.0
ecdsa==0.18.0
executing==2.0.1
flower==2.0.1
future==0.18.3
humanize==4.9.0
icdiff==2.0.7
idna==3.6
ipython==8.18.1
jedi==0.19.1
kombu==5.3.4
lxml==4.9.3
MarkupSafe==2.1.3
matplotlib-inline==0.1.6
munch==4.0.0
packaging==23.2
parso==0.8.3
pexpect==4.9.0
Pillow==10.1.0
pprintpp==0.4.0
prometheus-client==0.19.0
prompt-toolkit==3.0.41
psycopg2==2.9.9
ptyprocess==0.7.0
pure-eval==0.2.2
pyasn1==0.5.1
pyasn1-modules==0.3.0
Pygments==2.17.2
python-dateutil==2.8.2
python-dotenv==1.0.0
python-jose==3.3.0
pytz==2023.3.post1
redis==5.0.1
reportlab==4.0.7
requests==2.31.0
requests-toolbelt==1.0.0
rsa==4.9
setuptools==69.0.2
six==1.16.0
sorl-thumbnail==12.10.0
sqlparse==0.4.4
stack-data==0.6.3
tornado==6.4
traitlets==5.14.0
typing_extensions==4.8.0
tzdata==2023.3
urllib3==2.1.0
vine==5.1.0
wcwidth==0.2.12
webencodings==0.5.1
Werkzeug==3.0.1
xmltodict==0.13.0

Actual Behavior

Stacktrace copied from stackoverflow, as mine is much more cluttered:

celery beat v5.3.4 (emerald-rush) is starting.
__    -    ... __   -        _
LocalTime -> 2023-11-03 10:48:13
Configuration ->
    . broker -> redis://redis:6379/0
    . loader -> celery.loaders.app.AppLoader
    . scheduler -> celery.beat.PersistentScheduler
    . db -> celerybeat-schedule
    . logfile -> [stderr]@%DEBUG
    . maxinterval -> 5.00 minutes (300s)
[2023-11-03 10:48:13,939: DEBUG/MainProcess] Setting default socket timeout to 30
[2023-11-03 10:48:13,940: INFO/MainProcess] beat: Starting...
[2023-11-03 10:48:13,945: CRITICAL/MainProcess] beat raised exception <class 'ModuleNotFoundError'>: ModuleNotFoundError("No module named 'backports'")
Traceback (most recent call last):
  File "/usr/local/lib/python3.10/shelve.py", line 111, in __getitem__
    value = self.cache[key]
KeyError: 'entries'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.10/site-packages/celery/apps/beat.py", line 113, in start_scheduler
    service.start()
  File "/usr/local/lib/python3.10/site-packages/celery/beat.py", line 634, in start
    humanize_seconds(self.scheduler.max_interval))
  File "/usr/local/lib/python3.10/site-packages/kombu/utils/objects.py", line 31, in __get__
    return super().__get__(instance, owner)
  File "/usr/local/lib/python3.10/functools.py", line 981, in __get__
    val = self.func(instance)
  File "/usr/local/lib/python3.10/site-packages/celery/beat.py", line 677, in scheduler
    return self.get_scheduler()
  File "/usr/local/lib/python3.10/site-packages/celery/beat.py", line 668, in get_scheduler
    return symbol_by_name(self.scheduler_cls, aliases=aliases)(
  File "/usr/local/lib/python3.10/site-packages/celery/beat.py", line 513, in __init__
    super().__init__(*args, **kwargs)
  File "/usr/local/lib/python3.10/site-packages/celery/beat.py", line 264, in __init__
    self.setup_schedule()
  File "/usr/local/lib/python3.10/site-packages/celery/beat.py", line 541, in setup_schedule
    self._create_schedule()
  File "/usr/local/lib/python3.10/site-packages/celery/beat.py", line 570, in _create_schedule
    self._store['entries']
  File "/usr/local/lib/python3.10/shelve.py", line 114, in __getitem__
    value = Unpickler(f).load()
ModuleNotFoundError: No module named 'backports'

Dec 10 '23 21:12 JanMalte

Removing the existing scheduler DB is solving the issue, but this should not be neccessary after a python version update/upgrade.

Dec 10 '23 21:12 JanMalte