Celery No module named 'future' after upgrading to 4.4.4

The Fix

pip install celery==4.4.5

Based on closed celery/celery issue #6148 · PR/commit linked

Production note: Most teams hit this during upgrades or environment changes. Roll out with a canary and smoke critical endpoints (health, OpenAPI/docs) before 100%.

Jump to Verify Open PR/Commit

@@ -1,4 +1,5 @@
 pytz>dev
 billiard>=3.6.3.0,<4.0
+future>=0.18.0
 kombu>=4.6.10,<4.7
 vine==1.3.0

repro.py

[2020-06-03 09:48:39,517: DEBUG/MainProcess] | Worker: Preparing bootsteps.
[2020-06-03 09:48:39,518: DEBUG/MainProcess] | Worker: Building graph...
[2020-06-03 09:48:39,518: DEBUG/MainProcess] | Worker: New boot order: {StateDB, Beat, Timer, Hub, Pool, Autoscaler, Consumer}
[2020-06-03 09:48:39,522: DEBUG/MainProcess] | Consumer: Preparing bootsteps.
[2020-06-03 09:48:39,522: DEBUG/MainProcess] | Consumer: Building graph...
[2020-06-03 09:48:39,538: DEBUG/MainProcess] | Consumer: New boot order: {Connection, Events, Heart, Mingle, Gossip, Agent, Tasks, Control, event loop}
[2020-06-03 09:48:39,540: CRITICAL/MainProcess] Unrecoverable error: ModuleNotFoundError("No module named 'future'")
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 "/usr/local/lib/python3.7/site-packages/celery/worker/worker.py", line 208, in start
    self.blueprint.start(self)
  File "/usr/local/lib/python3.7/site-packages/celery/bootsteps.py", line 115, in start
    self.on_start()
  File "/usr/local/lib/python3.7/site-packages/celery/apps/worker.py", line 139, in on_start
    self.emit_banner()
  File "/usr/local/lib/python3.7/site-packages/celery/apps/worker.py", line 154, in emit_banner
    ' \n', self.startup_info(artlines=not use_image))),
  File "/usr/local/lib/python3.7/site-packages/celery/apps/worker.py", line 217, in startup_info
    results=self.app.backend.as_uri(),
  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'

verify

Re-run the minimal reproduction on your broken version, then apply the fix and re-run.

fix.md

Option A — Upgrade to fixed release\npip install celery==4.4.5\nWhen NOT to use: Do not apply this fix if the 'future' package is already installed.\n\n

Why This Fix Works in Production

Trigger: [2020-06-03 09:48:39,517: DEBUG/MainProcess] | Worker: Preparing bootsteps.
Mechanism: Added a missing dependency on 'future' to resolve the ModuleNotFoundError after upgrading to celery 4.4.4.
Why the fix works: Added a missing dependency on 'future' to resolve the ModuleNotFoundError after upgrading to celery 4.4.4. (first fixed release: 4.4.5).

Production impact:

If left unfixed, the same config can fail only in production (env differences), causing startup failures or partial feature outages.

Why This Breaks in Prod

Shows up under Python 3.7 in real deployments (not just unit tests).
Surfaces as: [2020-06-03 09:48:39,517: DEBUG/MainProcess] | Worker: Preparing bootsteps.

Proof / Evidence

GitHub issue: #6148
Fix PR: https://github.com/celery/celery/pull/6146
First fixed release: 4.4.5
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.85
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.24

Discussion

High-signal excerpts from the issue thread (symptoms, repros, edge-cases).

Jump to Sources Open on GitHub

“Looks like this was fixed in https://github.com/celery/celery/pull/6146.”

@solarissmoke · 2020-06-03 · confirmation · source

“fixed on master expect another minor release ver very soon.”

@auvipy · 2020-06-03 · source

“@solarissmoke I saw that commit and if you check v4.4.4's commits it's included, but still if you install celery==4.4.4 from pypi it will crash with…”

@menecio · 2020-06-03 · source

“You are reading the diff wrong - this commit is _not_ part of the 4.4.4 release, hence why it's appearing in the diff. See the…”

@solarissmoke · 2020-06-03 · source

Failure Signature (Search String)

[2020-06-03 09:48:39,517: DEBUG/MainProcess] | Worker: Preparing bootsteps.

Error Message

Stack trace

error.txt

Error Message
-------------
[2020-06-03 09:48:39,517: DEBUG/MainProcess] | Worker: Preparing bootsteps.
[2020-06-03 09:48:39,518: DEBUG/MainProcess] | Worker: Building graph...
[2020-06-03 09:48:39,518: DEBUG/MainProcess] | Worker: New boot order: {StateDB, Beat, Timer, Hub, Pool, Autoscaler, Consumer}
[2020-06-03 09:48:39,522: DEBUG/MainProcess] | Consumer: Preparing bootsteps.
[2020-06-03 09:48:39,522: DEBUG/MainProcess] | Consumer: Building graph...
[2020-06-03 09:48:39,538: DEBUG/MainProcess] | Consumer: New boot order: {Connection, Events, Heart, Mingle, Gossip, Agent, Tasks, Control, event loop}
[2020-06-03 09:48:39,540: CRITICAL/MainProcess] Unrecoverable error: ModuleNotFoundError("No module named 'future'")
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 "/usr/local/lib/python3.7/site-packages/celery/worker/worker.py", line 208, in start
    self.blueprint.start(self)
  File "/usr/local/lib/python3.7/site-packages/celery/bootsteps.py", line 115, in start
    self.on_start()
  File "/usr/local/lib/python3.7/site-packages/celery/apps/worker.py", line 139, in on_start
    self.emit_banner()
  File "/usr/local/lib/python3.7/site-packages/celery/apps/worke
... (truncated) ...

Minimal Reproduction

repro.py

[2020-06-03 09:48:39,517: DEBUG/MainProcess] | Worker: Preparing bootsteps.
[2020-06-03 09:48:39,518: DEBUG/MainProcess] | Worker: Building graph...
[2020-06-03 09:48:39,518: DEBUG/MainProcess] | Worker: New boot order: {StateDB, Beat, Timer, Hub, Pool, Autoscaler, Consumer}
[2020-06-03 09:48:39,522: DEBUG/MainProcess] | Consumer: Preparing bootsteps.
[2020-06-03 09:48:39,522: DEBUG/MainProcess] | Consumer: Building graph...
[2020-06-03 09:48:39,538: DEBUG/MainProcess] | Consumer: New boot order: {Connection, Events, Heart, Mingle, Gossip, Agent, Tasks, Control, event loop}
[2020-06-03 09:48:39,540: CRITICAL/MainProcess] Unrecoverable error: ModuleNotFoundError("No module named 'future'")
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 "/usr/local/lib/python3.7/site-packages/celery/worker/worker.py", line 208, in start
    self.blueprint.start(self)
  File "/usr/local/lib/python3.7/site-packages/celery/bootsteps.py", line 115, in start
    self.on_start()
  File "/usr/local/lib/python3.7/site-packages/celery/apps/worker.py", line 139, in on_start
    self.emit_banner()
  File "/usr/local/lib/python3.7/site-packages/celery/apps/worker.py", line 154, in emit_banner
    ' \n', self.startup_info(artlines=not use_image))),
  File "/usr/local/lib/python3.7/site-packages/celery/apps/worker.py", line 217, in startup_info
    results=self.app.backend.as_uri(),
  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'

Environment

Python: 3.7

What Broke

Builds fail with ModuleNotFoundError for 'future' package after upgrade.

Fix Options (Details)

Option A — Upgrade to fixed release Safe default (recommended)

pip install celery==4.4.5

When NOT to use: Do not apply this fix if the 'future' package is already installed.

Use when you can deploy the upstream fix. It is usually lower-risk than long-lived workarounds.

Fix reference: https://github.com/celery/celery/pull/6146

First fixed release: 4.4.5

Last verified: 2026-02-09. Validate in your environment.

When NOT to Use This Fix

Do not apply this fix if the 'future' package is already installed.

Verify Fix

verify

Re-run the minimal reproduction on your broken version, then apply the fix and re-run.

Did This Fix Work in Your Case?

Quick signal helps us prioritize which fixes to verify and improve.

Prevention

Capture the exact failing error string in logs and tests so you can reproduce via a minimal script.
Pin production dependencies and upgrade only with a reproducible test that hits the failing path.

Version Compatibility Table

Version	Status
4.4.5	Fixed

Related Issues

No related fixes found.

Cluster: celery:configuration-error Celery hub Celery best practices All hubs All clusters

Related clusters: Data consistency Duplicates Duplicate processing

Sources

We don’t republish the full GitHub discussion text. Use the links above for context.

Celery No module named 'future' after upgrading to 4.4.4 (Fix)