Issue 1:
without running any celery worker

celery --version

4.3.1 (rhubarb)

celery inspect ping

Error: No nodes replied within time constraint.

echo $?

69

pip install celery==5.0.5

celery --version

5.0.5 (singularity)

celery inspect ping

No nodes replied within time constraint

echo $?

0

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: 5.0.x

celery report Output:

Steps to Reproduce

Required Dependencies

Python Packages

Other Dependencies

Minimally Reproducible Test Case

See start Issue

Expected Behavior

Exit with intended value

Actual Behavior

Exit with 0

Issue 2:
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

I could not find any statement in the documentation (or bug reports) about whether or not Celery supports interoperability across versions among the participants using a Celery queue.

Background: I am working on upgrading a development environment that has long been unmaintained. It has a user component that distributes work through celery to 100+ workers. I am upgrading the user component, including a newer Celery version (4,4,7) than the workers (3,1.26). That almost works but not entirely; digging in internal structures shows "error" strings, the details of which are not pertinent to this request and I would have to dig through the Celery code and messages to understand them. First I'll downgrade so all parts are using the same version to see if that fixes my problem.

What I really wanted to do was to see if Celery claims support for interoperability across versions. But I could not find anything in the documentation regarding cross-version interoperability or non-support of such a thing. Because Celery enables distribution of work, it would be great if here was some interoperability across versions, but I cannot even determine if that is an intended part of the design.

Suggestions

First, I'm just looking for a statement about support or non-support of interoperability across versions. If it is supported, then something about the constraints about what versions can be mixed, e.g. it's ok across minor versions but not major versions.

Maybe this is documented somewhere, but I could not come up with any searches to find it. This sort of thing does not lend itself to nice targeted searches.