Encounter "Unknown changelog format 'None'" when generating changelog

[gsemet]

Description

I have the following error starting 3.12:

poetry run cz changelog \
                --file-name docs/source/changelog.md.sections \
                --unreleased-version UNRELEASED_VERSION
Unknown changelog format 'None'

reverted to 3.11 works fine

Steps to reproduce

poetry run cz changelog \
                --file-name docs/source/changelog.md.sections \
                --unreleased-version UNRELEASED_VERSION

Current behavior

Unknown changelog format 'None'

Desired behavior

changelog well generated

Screenshots

No response

Environment

cz 3.12

[anthonyfinch]

I have just been bitten by this one too. @gsemet thanks for version workaround, it was blocking our builds!

[Lee-W]

HI @gsemet @anthonyfinch , could you please provide more detail on this issue? I'm not able to reproduce it. Might need to know how the changelog looks like and what are some of the example commits