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Fix cron description treating "?" as a day-of-month/day-of-week conflict - #72292

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Fix cron description treating "?" as a day-of-month/day-of-week conflict#72292
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@ethanstonerethanstoner commented Aug 30, 2026

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croniter accepts ? in the day-of-month and day-of-week fields and expands it to * (croniter.py: "currently just trade ? as *"), so 0 0 ? * MON schedules exactly like 0 0 * * MON. Airflow's docs explicitly point users at croniter's extended syntax in cron.rst.

CronMixin._describe_with_dom_dow_fix compares the DOM/DOW fields against "*" only, so a ? counts as a restriction and the description gets split into a bogus "or" clause that claims a run which never happens.

Reproduction (on main, before this change)

$ uv run --project airflow-core python -c '...'
croniter 6.2.4 | cron-descriptor 2.1.0
expression : 0 0 ? * MON
actual runs : ['2026-01-05', '2026-01-12', '2026-01-19'] # Mondays only
description : 'At 00:00 (or) At 00:00, only on Monday' # <- claims a daily midnight run
expression : 0 0 1 * ?
actual runs : ['2026-02-01', '2026-03-01', '2026-04-01'] # 1st of month only
description : 'At 00:00, on day 1 of the month (or) At 00:00'

The description is persisted as DagModel.timetable_description and surfaced in the UI, the REST API (DAGDetailsResponse.timetable_description) and airflow dags details, so the user is shown a schedule that contradicts what the scheduler actually does.

After

'0 0 ? * MON' -> 'At 00:00, only on Monday'
'0 0 1 * ?' -> 'At 00:00, on day 1 of the month'
'0 0 15 * 1' -> 'At 00:00, on day 15 of the month (or) At 00:00, only on Monday'

Genuine DOM/DOW conflicts keep the existing "or" explanation added in #54644.

Testing

Three parametrized cases added to airflow-core/tests/unit/timetables/test_cron_mixin.py, each asserting the ? form describes identically to its * equivalent. They fail on unpatched main:

3 failed, 3 passed
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-day-of-month]
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-day-of-week]
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-both]

and pass with the fix. Full suite and static checks:

  • uv run --project airflow-core pytest airflow-core/tests/unit/timetables/ — 256 passed
  • prek run --files airflow-core/src/airflow/timetables/_cron.py airflow-core/tests/unit/timetables/test_cron_mixin.py — all hooks pass
  • prek run mypy-airflow-core --files airflow-core/src/airflow/timetables/_cron.py — passed

No newsfragment: this is a bugfix to a generated description string, not a significant user-facing change. Happy to add one if a maintainer prefers.

Was generative AI tooling used to co-author this PR?
  • Yes (please specify the tool below)

Generated-by: Claude Code following the guidelines

The defect was found by auditing airflow/timetables/, reproduced against unmodified main, and every command and output quoted above was actually run locally. I have reviewed and understand the change; it is two lines of logic plus a test.

@ethanstoner
Fix cron description treating "?" as a day-of-month/day-of-week conflict
72cd352
croniter accepts "?" in the day-of-month and day-of-week fields and expands
it to "*", so "0 0 ? * MON" schedules exactly like "0 0 * * MON". The
DOM/DOW conflict check compared the two fields against "*" only, so a "?"
counted as a restriction and the generated description was split into a
bogus "or" clause:
0 0 ? * MON -> "At 00:00 (or) At 00:00, only on Monday"
0 0 1 * ? -> "At 00:00, on day 1 of the month (or) At 00:00"
The extra clause claims a daily midnight run that never happens. This
description is stored as DagModel.timetable_description and shown in the
UI, the REST API and "airflow dags details".
Treat "?" as unrestricted alongside "*". Genuine DOM/DOW conflicts such as
"0 0 15 * 1" keep the existing "or" explanation.
Signed-off-by: Ethan Stoner <ethanstoner08@gmail.com>
@boring-cyborg

boring-cyborgBot commented Aug 30, 2026

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Congratulations on your first Pull Request and welcome to the Apache Airflow community! If you have any issues or are unsure about any anything please check our Contributors' Guide
Here are some useful points:

  • Pay attention to the quality of your code (ruff, mypy and type annotations). Our prek-hooks will help you with that.
  • In case of a new feature add useful documentation (in docstrings or in docs/ directory). Adding a new operator? Check this short guide Consider adding an example Dag that shows how users should use it.
  • Consider using Breeze environment for testing locally, it's a heavy docker but it ships with a working Airflow and a lot of integrations.
  • Be patient and persistent. It might take some time to get a review or get the final approval from Committers.
  • Please follow ASF Code of Conduct for all communication including (but not limited to) comments on Pull Requests, Mailing list and Slack.
  • Be sure to read the Airflow Coding style.
  • Always keep your Pull Requests rebased, otherwise your build might fail due to changes not related to your commits.
    Apache Airflow is a community-driven project and together we are making it better 🚀.
    In case of doubts contact the developers at:
    Mailing List: dev@airflow.apache.org
    Slack: https://s.apache.org/airflow-slack

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Fix cron description treating "?" as a day-of-month/day-of-week conflict by ethanstoner · Pull Request #72292 · apache/airflow · GitHub
Skip to content
Fix cron description treating "?" as a day-of-month/day-of-week conflict - #72292
Open
ethanstoner wants to merge 1 commit into
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ethanstoner:fix-cron-question-mark-description
Open
Fix cron description treating "?" as a day-of-month/day-of-week conflict#72292
ethanstoner wants to merge 1 commit into
apache:mainfrom 
ethanstoner:fix-cron-question-mark-description
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@ethanstonerethanstoner
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Aug 30, 2026

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croniter accepts ? in the day-of-month and day-of-week fields and expands it to * (croniter.py: "currently just trade ? as *"), so 0 0 ? * MON schedules exactly like 0 0 * * MON. Airflow's docs explicitly point users at croniter's extended syntax in cron.rst.
CronMixin._describe_with_dom_dow_fix compares the DOM/DOW fields against "*" only, so a ? counts as a restriction and the description gets split into a bogus "or" clause that claims a run which never happens.
Reproduction (on main, before this change)
$ uv run --project airflow-core python -c '...'
croniter 6.2.4 | cron-descriptor 2.1.0
expression : 0 0 ? * MON
actual runs : ['2026-01-05', '2026-01-12', '2026-01-19'] # Mondays only
description : 'At 00:00 (or) At 00:00, only on Monday' # <- claims a daily midnight run
expression : 0 0 1 * ?
actual runs : ['2026-02-01', '2026-03-01', '2026-04-01'] # 1st of month only
description : 'At 00:00, on day 1 of the month (or) At 00:00'

The description is persisted as DagModel.timetable_description and surfaced in the UI, the REST API (DAGDetailsResponse.timetable_description) and airflow dags details, so the user is shown a schedule that contradicts what the scheduler actually does.
After
'0 0 ? * MON' -> 'At 00:00, only on Monday'
'0 0 1 * ?' -> 'At 00:00, on day 1 of the month'
'0 0 15 * 1' -> 'At 00:00, on day 15 of the month (or) At 00:00, only on Monday'

Genuine DOM/DOW conflicts keep the existing "or" explanation added in #54644.
Testing
Three parametrized cases added to airflow-core/tests/unit/timetables/test_cron_mixin.py, each asserting the ? form describes identically to its * equivalent. They fail on unpatched main:
3 failed, 3 passed
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-day-of-month]
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-day-of-week]
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-both]

and pass with the fix. Full suite and static checks:
  • uv run --project airflow-core pytest airflow-core/tests/unit/timetables/ — 256 passed
  • prek run --files airflow-core/src/airflow/timetables/_cron.py airflow-core/tests/unit/timetables/test_cron_mixin.py — all hooks pass
  • prek run mypy-airflow-core --files airflow-core/src/airflow/timetables/_cron.py — passed
No newsfragment: this is a bugfix to a generated description string, not a significant user-facing change. Happy to add one if a maintainer prefers.
Was generative AI tooling used to co-author this PR?
  •  Yes (please specify the tool below)
Generated-by: Claude Code following the guidelines
The defect was found by auditing airflow/timetables/, reproduced against unmodified main, and every command and output quoted above was actually run locally. I have reviewed and understand the change; it is two lines of logic plus a test.
@ethanstoner
Fix cron description treating "?" as a day-of-month/day-of-week conflict
72cd352
croniter accepts "?" in the day-of-month and day-of-week fields and expands
it to "*", so "0 0 ? * MON" schedules exactly like "0 0 * * MON". The
DOM/DOW conflict check compared the two fields against "*" only, so a "?"
counted as a restriction and the generated description was split into a
bogus "or" clause:
0 0 ? * MON -> "At 00:00 (or) At 00:00, only on Monday"
0 0 1 * ? -> "At 00:00, on day 1 of the month (or) At 00:00"
The extra clause claims a daily midnight run that never happens. This
description is stored as DagModel.timetable_description and shown in the
UI, the REST API and "airflow dags details".
Treat "?" as unrestricted alongside "*". Genuine DOM/DOW conflicts such as
"0 0 15 * 1" keep the existing "or" explanation.
Signed-off-by: Ethan Stoner <ethanstoner08@gmail.com>
@boring-cyborg
boring-cyborgBot
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Aug 30, 2026

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Congratulations on your first Pull Request and welcome to the Apache Airflow community! If you have any issues or are unsure about any anything please check our Contributors' Guide

Here are some useful points:
  • Pay attention to the quality of your code (ruff, mypy and type annotations). Our prek-hooks will help you with that.
  • In case of a new feature add useful documentation (in docstrings or in docs/ directory). Adding a new operator? Check this short guide Consider adding an example Dag that shows how users should use it.
  • Consider using Breeze environment for testing locally, it's a heavy docker but it ships with a working Airflow and a lot of integrations.
  • Be patient and persistent. It might take some time to get a review or get the final approval from Committers.
  • Please follow ASF Code of Conduct for all communication including (but not limited to) comments on Pull Requests, Mailing list and Slack.
  • Be sure to read the Airflow Coding style.
  • Always keep your Pull Requests rebased, otherwise your build might fail due to changes not related to your commits.
    
Apache Airflow is a community-driven project and together we are making it better 🚀.
    
In case of doubts contact the developers at:
    
Mailing List: dev@airflow.apache.org
    
Slack: https://s.apache.org/airflow-slack
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Fix cron description treating "?" as a day-of-month/day-of-week conflict by ethanstoner · Pull Request #72292 · apache/airflow · GitHub
Skip to content
Fix cron description treating "?" as a day-of-month/day-of-week conflict - #72292
Open
ethanstoner wants to merge 1 commit into
apache:mainfrom 
ethanstoner:fix-cron-question-mark-description
Open
Fix cron description treating "?" as a day-of-month/day-of-week conflict#72292
ethanstoner wants to merge 1 commit into
apache:mainfrom 
ethanstoner:fix-cron-question-mark-description
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@ethanstoner
@ethanstonerethanstoner
commented
Aug 30, 2026

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croniter accepts ? in the day-of-month and day-of-week fields and expands it to * (croniter.py: "currently just trade ? as *"), so 0 0 ? * MON schedules exactly like 0 0 * * MON. Airflow's docs explicitly point users at croniter's extended syntax in cron.rst.
CronMixin._describe_with_dom_dow_fix compares the DOM/DOW fields against "*" only, so a ? counts as a restriction and the description gets split into a bogus "or" clause that claims a run which never happens.
Reproduction (on main, before this change)
$ uv run --project airflow-core python -c '...'
croniter 6.2.4 | cron-descriptor 2.1.0
expression : 0 0 ? * MON
actual runs : ['2026-01-05', '2026-01-12', '2026-01-19'] # Mondays only
description : 'At 00:00 (or) At 00:00, only on Monday' # <- claims a daily midnight run
expression : 0 0 1 * ?
actual runs : ['2026-02-01', '2026-03-01', '2026-04-01'] # 1st of month only
description : 'At 00:00, on day 1 of the month (or) At 00:00'

The description is persisted as DagModel.timetable_description and surfaced in the UI, the REST API (DAGDetailsResponse.timetable_description) and airflow dags details, so the user is shown a schedule that contradicts what the scheduler actually does.
After
'0 0 ? * MON' -> 'At 00:00, only on Monday'
'0 0 1 * ?' -> 'At 00:00, on day 1 of the month'
'0 0 15 * 1' -> 'At 00:00, on day 15 of the month (or) At 00:00, only on Monday'

Genuine DOM/DOW conflicts keep the existing "or" explanation added in #54644.
Testing
Three parametrized cases added to airflow-core/tests/unit/timetables/test_cron_mixin.py, each asserting the ? form describes identically to its * equivalent. They fail on unpatched main:
3 failed, 3 passed
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-day-of-month]
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-day-of-week]
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-both]

and pass with the fix. Full suite and static checks:
  • uv run --project airflow-core pytest airflow-core/tests/unit/timetables/ — 256 passed
  • prek run --files airflow-core/src/airflow/timetables/_cron.py airflow-core/tests/unit/timetables/test_cron_mixin.py — all hooks pass
  • prek run mypy-airflow-core --files airflow-core/src/airflow/timetables/_cron.py — passed
No newsfragment: this is a bugfix to a generated description string, not a significant user-facing change. Happy to add one if a maintainer prefers.
Was generative AI tooling used to co-author this PR?
  •  Yes (please specify the tool below)
Generated-by: Claude Code following the guidelines
The defect was found by auditing airflow/timetables/, reproduced against unmodified main, and every command and output quoted above was actually run locally. I have reviewed and understand the change; it is two lines of logic plus a test.
@ethanstoner
Fix cron description treating "?" as a day-of-month/day-of-week conflict
72cd352
croniter accepts "?" in the day-of-month and day-of-week fields and expands
it to "*", so "0 0 ? * MON" schedules exactly like "0 0 * * MON". The
DOM/DOW conflict check compared the two fields against "*" only, so a "?"
counted as a restriction and the generated description was split into a
bogus "or" clause:
0 0 ? * MON -> "At 00:00 (or) At 00:00, only on Monday"
0 0 1 * ? -> "At 00:00, on day 1 of the month (or) At 00:00"
The extra clause claims a daily midnight run that never happens. This
description is stored as DagModel.timetable_description and shown in the
UI, the REST API and "airflow dags details".
Treat "?" as unrestricted alongside "*". Genuine DOM/DOW conflicts such as
"0 0 15 * 1" keep the existing "or" explanation.
Signed-off-by: Ethan Stoner <ethanstoner08@gmail.com>
@boring-cyborg
boring-cyborgBot
commented
Aug 30, 2026

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Congratulations on your first Pull Request and welcome to the Apache Airflow community! If you have any issues or are unsure about any anything please check our Contributors' Guide

Here are some useful points:
  • Pay attention to the quality of your code (ruff, mypy and type annotations). Our prek-hooks will help you with that.
  • In case of a new feature add useful documentation (in docstrings or in docs/ directory). Adding a new operator? Check this short guide Consider adding an example Dag that shows how users should use it.
  • Consider using Breeze environment for testing locally, it's a heavy docker but it ships with a working Airflow and a lot of integrations.
  • Be patient and persistent. It might take some time to get a review or get the final approval from Committers.
  • Please follow ASF Code of Conduct for all communication including (but not limited to) comments on Pull Requests, Mailing list and Slack.
  • Be sure to read the Airflow Coding style.
  • Always keep your Pull Requests rebased, otherwise your build might fail due to changes not related to your commits.
    
Apache Airflow is a community-driven project and together we are making it better 🚀.
    
In case of doubts contact the developers at:
    
Mailing List: dev@airflow.apache.org
    
Slack: https://s.apache.org/airflow-slack
Sign up for freeto join this conversation on GitHub.
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Fix cron description treating "?" as a day-of-month/day-of-week conflict by ethanstoner · Pull Request #72292 · apache/airflow · GitHub
Skip to content
Fix cron description treating "?" as a day-of-month/day-of-week conflict - #72292
Open
ethanstoner wants to merge 1 commit into
apache:mainfrom 
ethanstoner:fix-cron-question-mark-description
Open
Fix cron description treating "?" as a day-of-month/day-of-week conflict#72292
ethanstoner wants to merge 1 commit into
apache:mainfrom 
ethanstoner:fix-cron-question-mark-description
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@ethanstonerethanstoner
commented
Aug 30, 2026

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croniter accepts ? in the day-of-month and day-of-week fields and expands it to * (croniter.py: "currently just trade ? as *"), so 0 0 ? * MON schedules exactly like 0 0 * * MON. Airflow's docs explicitly point users at croniter's extended syntax in cron.rst.
CronMixin._describe_with_dom_dow_fix compares the DOM/DOW fields against "*" only, so a ? counts as a restriction and the description gets split into a bogus "or" clause that claims a run which never happens.
Reproduction (on main, before this change)
$ uv run --project airflow-core python -c '...'
croniter 6.2.4 | cron-descriptor 2.1.0
expression : 0 0 ? * MON
actual runs : ['2026-01-05', '2026-01-12', '2026-01-19'] # Mondays only
description : 'At 00:00 (or) At 00:00, only on Monday' # <- claims a daily midnight run
expression : 0 0 1 * ?
actual runs : ['2026-02-01', '2026-03-01', '2026-04-01'] # 1st of month only
description : 'At 00:00, on day 1 of the month (or) At 00:00'

The description is persisted as DagModel.timetable_description and surfaced in the UI, the REST API (DAGDetailsResponse.timetable_description) and airflow dags details, so the user is shown a schedule that contradicts what the scheduler actually does.
After
'0 0 ? * MON' -> 'At 00:00, only on Monday'
'0 0 1 * ?' -> 'At 00:00, on day 1 of the month'
'0 0 15 * 1' -> 'At 00:00, on day 15 of the month (or) At 00:00, only on Monday'

Genuine DOM/DOW conflicts keep the existing "or" explanation added in #54644.
Testing
Three parametrized cases added to airflow-core/tests/unit/timetables/test_cron_mixin.py, each asserting the ? form describes identically to its * equivalent. They fail on unpatched main:
3 failed, 3 passed
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-day-of-month]
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-day-of-week]
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-both]

and pass with the fix. Full suite and static checks:
  • uv run --project airflow-core pytest airflow-core/tests/unit/timetables/ — 256 passed
  • prek run --files airflow-core/src/airflow/timetables/_cron.py airflow-core/tests/unit/timetables/test_cron_mixin.py — all hooks pass
  • prek run mypy-airflow-core --files airflow-core/src/airflow/timetables/_cron.py — passed
No newsfragment: this is a bugfix to a generated description string, not a significant user-facing change. Happy to add one if a maintainer prefers.
Was generative AI tooling used to co-author this PR?
  •  Yes (please specify the tool below)
Generated-by: Claude Code following the guidelines
The defect was found by auditing airflow/timetables/, reproduced against unmodified main, and every command and output quoted above was actually run locally. I have reviewed and understand the change; it is two lines of logic plus a test.
@ethanstoner
Fix cron description treating "?" as a day-of-month/day-of-week conflict
72cd352
croniter accepts "?" in the day-of-month and day-of-week fields and expands
it to "*", so "0 0 ? * MON" schedules exactly like "0 0 * * MON". The
DOM/DOW conflict check compared the two fields against "*" only, so a "?"
counted as a restriction and the generated description was split into a
bogus "or" clause:
0 0 ? * MON -> "At 00:00 (or) At 00:00, only on Monday"
0 0 1 * ? -> "At 00:00, on day 1 of the month (or) At 00:00"
The extra clause claims a daily midnight run that never happens. This
description is stored as DagModel.timetable_description and shown in the
UI, the REST API and "airflow dags details".
Treat "?" as unrestricted alongside "*". Genuine DOM/DOW conflicts such as
"0 0 15 * 1" keep the existing "or" explanation.
Signed-off-by: Ethan Stoner <ethanstoner08@gmail.com>
@boring-cyborg
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Aug 30, 2026

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Congratulations on your first Pull Request and welcome to the Apache Airflow community! If you have any issues or are unsure about any anything please check our Contributors' Guide

Here are some useful points:
  • Pay attention to the quality of your code (ruff, mypy and type annotations). Our prek-hooks will help you with that.
  • In case of a new feature add useful documentation (in docstrings or in docs/ directory). Adding a new operator? Check this short guide Consider adding an example Dag that shows how users should use it.
  • Consider using Breeze environment for testing locally, it's a heavy docker but it ships with a working Airflow and a lot of integrations.
  • Be patient and persistent. It might take some time to get a review or get the final approval from Committers.
  • Please follow ASF Code of Conduct for all communication including (but not limited to) comments on Pull Requests, Mailing list and Slack.
  • Be sure to read the Airflow Coding style.
  • Always keep your Pull Requests rebased, otherwise your build might fail due to changes not related to your commits.
    
Apache Airflow is a community-driven project and together we are making it better 🚀.
    
In case of doubts contact the developers at:
    
Mailing List: dev@airflow.apache.org
    
Slack: https://s.apache.org/airflow-slack
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Fix cron description treating "?" as a day-of-month/day-of-week conflict by ethanstoner · Pull Request #72292 · apache/airflow · GitHub
Skip to content
Fix cron description treating "?" as a day-of-month/day-of-week conflict - #72292
Open
ethanstoner wants to merge 1 commit into
apache:mainfrom 
ethanstoner:fix-cron-question-mark-description
Open
Fix cron description treating "?" as a day-of-month/day-of-week conflict#72292
ethanstoner wants to merge 1 commit into
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ethanstoner:fix-cron-question-mark-description
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@ethanstoner
@ethanstonerethanstoner
commented
Aug 30, 2026

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croniter accepts ? in the day-of-month and day-of-week fields and expands it to * (croniter.py: "currently just trade ? as *"), so 0 0 ? * MON schedules exactly like 0 0 * * MON. Airflow's docs explicitly point users at croniter's extended syntax in cron.rst.
CronMixin._describe_with_dom_dow_fix compares the DOM/DOW fields against "*" only, so a ? counts as a restriction and the description gets split into a bogus "or" clause that claims a run which never happens.
Reproduction (on main, before this change)
$ uv run --project airflow-core python -c '...'
croniter 6.2.4 | cron-descriptor 2.1.0
expression : 0 0 ? * MON
actual runs : ['2026-01-05', '2026-01-12', '2026-01-19'] # Mondays only
description : 'At 00:00 (or) At 00:00, only on Monday' # <- claims a daily midnight run
expression : 0 0 1 * ?
actual runs : ['2026-02-01', '2026-03-01', '2026-04-01'] # 1st of month only
description : 'At 00:00, on day 1 of the month (or) At 00:00'

The description is persisted as DagModel.timetable_description and surfaced in the UI, the REST API (DAGDetailsResponse.timetable_description) and airflow dags details, so the user is shown a schedule that contradicts what the scheduler actually does.
After
'0 0 ? * MON' -> 'At 00:00, only on Monday'
'0 0 1 * ?' -> 'At 00:00, on day 1 of the month'
'0 0 15 * 1' -> 'At 00:00, on day 15 of the month (or) At 00:00, only on Monday'

Genuine DOM/DOW conflicts keep the existing "or" explanation added in #54644.
Testing
Three parametrized cases added to airflow-core/tests/unit/timetables/test_cron_mixin.py, each asserting the ? form describes identically to its * equivalent. They fail on unpatched main:
3 failed, 3 passed
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-day-of-month]
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-day-of-week]
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-both]

and pass with the fix. Full suite and static checks:
  • uv run --project airflow-core pytest airflow-core/tests/unit/timetables/ — 256 passed
  • prek run --files airflow-core/src/airflow/timetables/_cron.py airflow-core/tests/unit/timetables/test_cron_mixin.py — all hooks pass
  • prek run mypy-airflow-core --files airflow-core/src/airflow/timetables/_cron.py — passed
No newsfragment: this is a bugfix to a generated description string, not a significant user-facing change. Happy to add one if a maintainer prefers.
Was generative AI tooling used to co-author this PR?
  •  Yes (please specify the tool below)
Generated-by: Claude Code following the guidelines
The defect was found by auditing airflow/timetables/, reproduced against unmodified main, and every command and output quoted above was actually run locally. I have reviewed and understand the change; it is two lines of logic plus a test.
@ethanstoner
Fix cron description treating "?" as a day-of-month/day-of-week conflict
72cd352
croniter accepts "?" in the day-of-month and day-of-week fields and expands
it to "*", so "0 0 ? * MON" schedules exactly like "0 0 * * MON". The
DOM/DOW conflict check compared the two fields against "*" only, so a "?"
counted as a restriction and the generated description was split into a
bogus "or" clause:
0 0 ? * MON -> "At 00:00 (or) At 00:00, only on Monday"
0 0 1 * ? -> "At 00:00, on day 1 of the month (or) At 00:00"
The extra clause claims a daily midnight run that never happens. This
description is stored as DagModel.timetable_description and shown in the
UI, the REST API and "airflow dags details".
Treat "?" as unrestricted alongside "*". Genuine DOM/DOW conflicts such as
"0 0 15 * 1" keep the existing "or" explanation.
Signed-off-by: Ethan Stoner <ethanstoner08@gmail.com>
@boring-cyborg
boring-cyborgBot
commented
Aug 30, 2026

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Congratulations on your first Pull Request and welcome to the Apache Airflow community! If you have any issues or are unsure about any anything please check our Contributors' Guide

Here are some useful points:
  • Pay attention to the quality of your code (ruff, mypy and type annotations). Our prek-hooks will help you with that.
  • In case of a new feature add useful documentation (in docstrings or in docs/ directory). Adding a new operator? Check this short guide Consider adding an example Dag that shows how users should use it.
  • Consider using Breeze environment for testing locally, it's a heavy docker but it ships with a working Airflow and a lot of integrations.
  • Be patient and persistent. It might take some time to get a review or get the final approval from Committers.
  • Please follow ASF Code of Conduct for all communication including (but not limited to) comments on Pull Requests, Mailing list and Slack.
  • Be sure to read the Airflow Coding style.
  • Always keep your Pull Requests rebased, otherwise your build might fail due to changes not related to your commits.
    
Apache Airflow is a community-driven project and together we are making it better 🚀.
    
In case of doubts contact the developers at:
    
Mailing List: dev@airflow.apache.org
    
Slack: https://s.apache.org/airflow-slack
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
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function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
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try {
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var __re = new RegExp('^' + ".*" + '
Fix cron description treating "?" as a day-of-month/day-of-week conflict by ethanstoner · Pull Request #72292 · apache/airflow · GitHub
Skip to content
Fix cron description treating "?" as a day-of-month/day-of-week conflict - #72292
Open
ethanstoner wants to merge 1 commit into
apache:mainfrom 
ethanstoner:fix-cron-question-mark-description
Open
Fix cron description treating "?" as a day-of-month/day-of-week conflict#72292
ethanstoner wants to merge 1 commit into
apache:mainfrom 
ethanstoner:fix-cron-question-mark-description
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@ethanstoner
@ethanstonerethanstoner
commented
Aug 30, 2026

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croniter accepts ? in the day-of-month and day-of-week fields and expands it to * (croniter.py: "currently just trade ? as *"), so 0 0 ? * MON schedules exactly like 0 0 * * MON. Airflow's docs explicitly point users at croniter's extended syntax in cron.rst.
CronMixin._describe_with_dom_dow_fix compares the DOM/DOW fields against "*" only, so a ? counts as a restriction and the description gets split into a bogus "or" clause that claims a run which never happens.
Reproduction (on main, before this change)
$ uv run --project airflow-core python -c '...'
croniter 6.2.4 | cron-descriptor 2.1.0
expression : 0 0 ? * MON
actual runs : ['2026-01-05', '2026-01-12', '2026-01-19'] # Mondays only
description : 'At 00:00 (or) At 00:00, only on Monday' # <- claims a daily midnight run
expression : 0 0 1 * ?
actual runs : ['2026-02-01', '2026-03-01', '2026-04-01'] # 1st of month only
description : 'At 00:00, on day 1 of the month (or) At 00:00'

The description is persisted as DagModel.timetable_description and surfaced in the UI, the REST API (DAGDetailsResponse.timetable_description) and airflow dags details, so the user is shown a schedule that contradicts what the scheduler actually does.
After
'0 0 ? * MON' -> 'At 00:00, only on Monday'
'0 0 1 * ?' -> 'At 00:00, on day 1 of the month'
'0 0 15 * 1' -> 'At 00:00, on day 15 of the month (or) At 00:00, only on Monday'

Genuine DOM/DOW conflicts keep the existing "or" explanation added in #54644.
Testing
Three parametrized cases added to airflow-core/tests/unit/timetables/test_cron_mixin.py, each asserting the ? form describes identically to its * equivalent. They fail on unpatched main:
3 failed, 3 passed
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-day-of-month]
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-day-of-week]
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-both]

and pass with the fix. Full suite and static checks:
  • uv run --project airflow-core pytest airflow-core/tests/unit/timetables/ — 256 passed
  • prek run --files airflow-core/src/airflow/timetables/_cron.py airflow-core/tests/unit/timetables/test_cron_mixin.py — all hooks pass
  • prek run mypy-airflow-core --files airflow-core/src/airflow/timetables/_cron.py — passed
No newsfragment: this is a bugfix to a generated description string, not a significant user-facing change. Happy to add one if a maintainer prefers.
Was generative AI tooling used to co-author this PR?
  •  Yes (please specify the tool below)
Generated-by: Claude Code following the guidelines
The defect was found by auditing airflow/timetables/, reproduced against unmodified main, and every command and output quoted above was actually run locally. I have reviewed and understand the change; it is two lines of logic plus a test.
@ethanstoner
Fix cron description treating "?" as a day-of-month/day-of-week conflict
72cd352
croniter accepts "?" in the day-of-month and day-of-week fields and expands
it to "*", so "0 0 ? * MON" schedules exactly like "0 0 * * MON". The
DOM/DOW conflict check compared the two fields against "*" only, so a "?"
counted as a restriction and the generated description was split into a
bogus "or" clause:
0 0 ? * MON -> "At 00:00 (or) At 00:00, only on Monday"
0 0 1 * ? -> "At 00:00, on day 1 of the month (or) At 00:00"
The extra clause claims a daily midnight run that never happens. This
description is stored as DagModel.timetable_description and shown in the
UI, the REST API and "airflow dags details".
Treat "?" as unrestricted alongside "*". Genuine DOM/DOW conflicts such as
"0 0 15 * 1" keep the existing "or" explanation.
Signed-off-by: Ethan Stoner <ethanstoner08@gmail.com>
@boring-cyborg
boring-cyborgBot
commented
Aug 30, 2026

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Congratulations on your first Pull Request and welcome to the Apache Airflow community! If you have any issues or are unsure about any anything please check our Contributors' Guide

Here are some useful points:
  • Pay attention to the quality of your code (ruff, mypy and type annotations). Our prek-hooks will help you with that.
  • In case of a new feature add useful documentation (in docstrings or in docs/ directory). Adding a new operator? Check this short guide Consider adding an example Dag that shows how users should use it.
  • Consider using Breeze environment for testing locally, it's a heavy docker but it ships with a working Airflow and a lot of integrations.
  • Be patient and persistent. It might take some time to get a review or get the final approval from Committers.
  • Please follow ASF Code of Conduct for all communication including (but not limited to) comments on Pull Requests, Mailing list and Slack.
  • Be sure to read the Airflow Coding style.
  • Always keep your Pull Requests rebased, otherwise your build might fail due to changes not related to your commits.
    
Apache Airflow is a community-driven project and together we are making it better 🚀.
    
In case of doubts contact the developers at:
    
Mailing List: dev@airflow.apache.org
    
Slack: https://s.apache.org/airflow-slack
Sign up for freeto join this conversation on GitHub.
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, 'i');
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(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Fix cron description treating "?" as a day-of-month/day-of-week conflict by ethanstoner · Pull Request #72292 · apache/airflow · GitHub
Skip to content
Fix cron description treating "?" as a day-of-month/day-of-week conflict - #72292
Open
ethanstoner wants to merge 1 commit into
apache:mainfrom 
ethanstoner:fix-cron-question-mark-description
Open
Fix cron description treating "?" as a day-of-month/day-of-week conflict#72292
ethanstoner wants to merge 1 commit into
apache:mainfrom 
ethanstoner:fix-cron-question-mark-description
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@ethanstoner
@ethanstonerethanstoner
commented
Aug 30, 2026

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croniter accepts ? in the day-of-month and day-of-week fields and expands it to * (croniter.py: "currently just trade ? as *"), so 0 0 ? * MON schedules exactly like 0 0 * * MON. Airflow's docs explicitly point users at croniter's extended syntax in cron.rst.
CronMixin._describe_with_dom_dow_fix compares the DOM/DOW fields against "*" only, so a ? counts as a restriction and the description gets split into a bogus "or" clause that claims a run which never happens.
Reproduction (on main, before this change)
$ uv run --project airflow-core python -c '...'
croniter 6.2.4 | cron-descriptor 2.1.0
expression : 0 0 ? * MON
actual runs : ['2026-01-05', '2026-01-12', '2026-01-19'] # Mondays only
description : 'At 00:00 (or) At 00:00, only on Monday' # <- claims a daily midnight run
expression : 0 0 1 * ?
actual runs : ['2026-02-01', '2026-03-01', '2026-04-01'] # 1st of month only
description : 'At 00:00, on day 1 of the month (or) At 00:00'

The description is persisted as DagModel.timetable_description and surfaced in the UI, the REST API (DAGDetailsResponse.timetable_description) and airflow dags details, so the user is shown a schedule that contradicts what the scheduler actually does.
After
'0 0 ? * MON' -> 'At 00:00, only on Monday'
'0 0 1 * ?' -> 'At 00:00, on day 1 of the month'
'0 0 15 * 1' -> 'At 00:00, on day 15 of the month (or) At 00:00, only on Monday'

Genuine DOM/DOW conflicts keep the existing "or" explanation added in #54644.
Testing
Three parametrized cases added to airflow-core/tests/unit/timetables/test_cron_mixin.py, each asserting the ? form describes identically to its * equivalent. They fail on unpatched main:
3 failed, 3 passed
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-day-of-month]
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-day-of-week]
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-both]

and pass with the fix. Full suite and static checks:
  • uv run --project airflow-core pytest airflow-core/tests/unit/timetables/ — 256 passed
  • prek run --files airflow-core/src/airflow/timetables/_cron.py airflow-core/tests/unit/timetables/test_cron_mixin.py — all hooks pass
  • prek run mypy-airflow-core --files airflow-core/src/airflow/timetables/_cron.py — passed
No newsfragment: this is a bugfix to a generated description string, not a significant user-facing change. Happy to add one if a maintainer prefers.
Was generative AI tooling used to co-author this PR?
  •  Yes (please specify the tool below)
Generated-by: Claude Code following the guidelines
The defect was found by auditing airflow/timetables/, reproduced against unmodified main, and every command and output quoted above was actually run locally. I have reviewed and understand the change; it is two lines of logic plus a test.
@ethanstoner
Fix cron description treating "?" as a day-of-month/day-of-week conflict
72cd352
croniter accepts "?" in the day-of-month and day-of-week fields and expands
it to "*", so "0 0 ? * MON" schedules exactly like "0 0 * * MON". The
DOM/DOW conflict check compared the two fields against "*" only, so a "?"
counted as a restriction and the generated description was split into a
bogus "or" clause:
0 0 ? * MON -> "At 00:00 (or) At 00:00, only on Monday"
0 0 1 * ? -> "At 00:00, on day 1 of the month (or) At 00:00"
The extra clause claims a daily midnight run that never happens. This
description is stored as DagModel.timetable_description and shown in the
UI, the REST API and "airflow dags details".
Treat "?" as unrestricted alongside "*". Genuine DOM/DOW conflicts such as
"0 0 15 * 1" keep the existing "or" explanation.
Signed-off-by: Ethan Stoner <ethanstoner08@gmail.com>
@boring-cyborg
boring-cyborgBot
commented
Aug 30, 2026

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Congratulations on your first Pull Request and welcome to the Apache Airflow community! If you have any issues or are unsure about any anything please check our Contributors' Guide

Here are some useful points:
  • Pay attention to the quality of your code (ruff, mypy and type annotations). Our prek-hooks will help you with that.
  • In case of a new feature add useful documentation (in docstrings or in docs/ directory). Adding a new operator? Check this short guide Consider adding an example Dag that shows how users should use it.
  • Consider using Breeze environment for testing locally, it's a heavy docker but it ships with a working Airflow and a lot of integrations.
  • Be patient and persistent. It might take some time to get a review or get the final approval from Committers.
  • Please follow ASF Code of Conduct for all communication including (but not limited to) comments on Pull Requests, Mailing list and Slack.
  • Be sure to read the Airflow Coding style.
  • Always keep your Pull Requests rebased, otherwise your build might fail due to changes not related to your commits.
    
Apache Airflow is a community-driven project and together we are making it better 🚀.
    
In case of doubts contact the developers at:
    
Mailing List: dev@airflow.apache.org
    
Slack: https://s.apache.org/airflow-slack
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Fix cron description treating "?" as a day-of-month/day-of-week conflict by ethanstoner · Pull Request #72292 · apache/airflow · GitHub
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Fix cron description treating "?" as a day-of-month/day-of-week conflict - #72292
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ethanstoner:fix-cron-question-mark-description
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Fix cron description treating "?" as a day-of-month/day-of-week conflict#72292
ethanstoner wants to merge 1 commit into
apache:mainfrom 
ethanstoner:fix-cron-question-mark-description
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@ethanstoner
@ethanstonerethanstoner
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Aug 30, 2026

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croniter accepts ? in the day-of-month and day-of-week fields and expands it to * (croniter.py: "currently just trade ? as *"), so 0 0 ? * MON schedules exactly like 0 0 * * MON. Airflow's docs explicitly point users at croniter's extended syntax in cron.rst.
CronMixin._describe_with_dom_dow_fix compares the DOM/DOW fields against "*" only, so a ? counts as a restriction and the description gets split into a bogus "or" clause that claims a run which never happens.
Reproduction (on main, before this change)
$ uv run --project airflow-core python -c '...'
croniter 6.2.4 | cron-descriptor 2.1.0
expression : 0 0 ? * MON
actual runs : ['2026-01-05', '2026-01-12', '2026-01-19'] # Mondays only
description : 'At 00:00 (or) At 00:00, only on Monday' # <- claims a daily midnight run
expression : 0 0 1 * ?
actual runs : ['2026-02-01', '2026-03-01', '2026-04-01'] # 1st of month only
description : 'At 00:00, on day 1 of the month (or) At 00:00'

The description is persisted as DagModel.timetable_description and surfaced in the UI, the REST API (DAGDetailsResponse.timetable_description) and airflow dags details, so the user is shown a schedule that contradicts what the scheduler actually does.
After
'0 0 ? * MON' -> 'At 00:00, only on Monday'
'0 0 1 * ?' -> 'At 00:00, on day 1 of the month'
'0 0 15 * 1' -> 'At 00:00, on day 15 of the month (or) At 00:00, only on Monday'

Genuine DOM/DOW conflicts keep the existing "or" explanation added in #54644.
Testing
Three parametrized cases added to airflow-core/tests/unit/timetables/test_cron_mixin.py, each asserting the ? form describes identically to its * equivalent. They fail on unpatched main:
3 failed, 3 passed
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-day-of-month]
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-day-of-week]
FAILED test_cron_mixin.py::test_question_mark_is_not_a_dom_dow_conflict[question-mark-both]

and pass with the fix. Full suite and static checks:
  • uv run --project airflow-core pytest airflow-core/tests/unit/timetables/ — 256 passed
  • prek run --files airflow-core/src/airflow/timetables/_cron.py airflow-core/tests/unit/timetables/test_cron_mixin.py — all hooks pass
  • prek run mypy-airflow-core --files airflow-core/src/airflow/timetables/_cron.py — passed
No newsfragment: this is a bugfix to a generated description string, not a significant user-facing change. Happy to add one if a maintainer prefers.
Was generative AI tooling used to co-author this PR?
  •  Yes (please specify the tool below)
Generated-by: Claude Code following the guidelines
The defect was found by auditing airflow/timetables/, reproduced against unmodified main, and every command and output quoted above was actually run locally. I have reviewed and understand the change; it is two lines of logic plus a test.
@ethanstoner
Fix cron description treating "?" as a day-of-month/day-of-week conflict
72cd352
croniter accepts "?" in the day-of-month and day-of-week fields and expands
it to "*", so "0 0 ? * MON" schedules exactly like "0 0 * * MON". The
DOM/DOW conflict check compared the two fields against "*" only, so a "?"
counted as a restriction and the generated description was split into a
bogus "or" clause:
0 0 ? * MON -> "At 00:00 (or) At 00:00, only on Monday"
0 0 1 * ? -> "At 00:00, on day 1 of the month (or) At 00:00"
The extra clause claims a daily midnight run that never happens. This
description is stored as DagModel.timetable_description and shown in the
UI, the REST API and "airflow dags details".
Treat "?" as unrestricted alongside "*". Genuine DOM/DOW conflicts such as
"0 0 15 * 1" keep the existing "or" explanation.
Signed-off-by: Ethan Stoner <ethanstoner08@gmail.com>
@boring-cyborg
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Aug 30, 2026

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Congratulations on your first Pull Request and welcome to the Apache Airflow community! If you have any issues or are unsure about any anything please check our Contributors' Guide

Here are some useful points:
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