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# What happens when a Data Check fails in a pipeline

> Choose whether a failed Mammoth Data Check pauses the pipeline or flags and continues, combine checks with Any or All, email people and use Monitor.
>
> Applies to: Where: View › Describe your transformation › Controls › Data Check › If check fails

Each **Data Check** has an *If check fails* setting: **Pause the pipeline** or **Flag and continue**. With several checks, **Any** or **All** decides what counts as a failure. Failed checks show in the pipeline and in **Monitor**, and can email people you choose.

## Combine several checks with Any or All

![Data Check with two checks, a Null percentage and a Unique values check, and the Any or All selector for If check fails](https://mammoth.io/docs/images/20260427_105204_anyVSall1.webp)

With two or more checks, the failure sentence reads *If [Any | All] check fails*. The toggle sets how results combine:

| Setting | The Data Check fails when |
| --- | --- |
| **Any** (default) | Any one check fails. Every check must pass. |
| **All** | Every check fails. One passing check keeps the pipeline going. |

**All** is more lenient than it sounds: it means all checks must fail to count as a failure. Use **Any** if one failed check should stop or flag the pipeline. Use **All** only when the checks are alternatives and passing one is enough.

## Decide what happens when a check fails

![If check fails choice with Pause the pipeline selected beside Flag and continue, a Notify on failure checkbox and an info banner](https://mammoth.io/docs/images/20261009_132022_DataCheck-IfCheckFails.webp)

| Setting | What happens |
| --- | --- |
| **Pause the pipeline** | The pipeline stops. Later tasks wait until the data is fixed or approved, or you change the threshold, and the pipeline runs again. Use it for financial reports, regulated outputs, or anywhere bad data must not reach the final output. |
| **Flag and continue** | The failure is flagged and the pipeline runs to the end. Use it for operational data that analysts can still use, or to track data quality without blocking. |

If **Notify on failure** is on, the email goes out whichever setting you choose.

### Email people when a check fails

Tick **Notify on failure** and choose at least one recipient from the project's members. The email includes:

- the View name, the project name and a link to the View;
- where the Data Check sits in the pipeline, for example task 3 of 8;
- the status and details of each check, including the measured value;
- whether the pipeline was paused.

## Read Data Check results and statuses

After a run, each Data Check shows one of four statuses:

| Status | Meaning |
| --- | --- |
| **Passed** | The checks met the Any or All rule |
| **Failed** | The checks did not meet the Any or All rule |
| **Not run** | The Data Check has not run yet |
| **Bypassed** | It was skipped in a partial rerun because it sits before the task you reran from |

Open the status to see the **Data Check** results: each check with its column, condition, result and status. If a check uses a column that is no longer there, the dialog asks you to edit the Data Check to fix it.

![Data Check Failed dialog with the failed check, run details and an Edit Data Check button](https://mammoth.io/docs/images/20261009_131917_DataCheck-Failed-Dialog.webp)

### Find failed Data Checks in Monitor

A failed Data Check appears in **Monitor**, on the **Needs Attention** tab, in the **Governance** section. It reads *Data check failed* with a summary such as *1 of 2 checks failed*. Click **Review** to open the View.

![Monitor Needs Attention tab with an Errors section listing an error running a pipeline and a Governance section listing Data check failed with the summary 1 of 1 checks failed](https://mammoth.io/docs/images/20261009_130549_Monitor-NeedsAttention-Governance-DataCheckFailed.webp)

The item clears once you fix the data and the pipeline runs successfully.

## Troubleshooting a Data Check

| Symptom | Cause | Fix |
| --- | --- | --- |
| The pipeline stopped and later tasks didn't run | A Data Check set to **Pause the pipeline** failed | Open the status, fix the data or change the threshold, then run the pipeline again |
| A check fails even though only one rule broke | **Any** is selected, so one failed check fails the whole Data Check | Expected. Switch to **All** only if the checks are alternatives. |
| A check never fails although rules break | **All** is selected, so every check must fail | Switch to **Any** |
| The results dialog asks you to edit the Data Check | A check uses a column that no longer exists | Edit the Data Check and pick an existing column |
| The Data Check shows **Bypassed** | You reran from a task after it | Run the full pipeline to test it again |

## Related

- [Data Check types](https://mammoth.io/docs/learn/clean-and-shape/data-check-types/): the rules a check can test.
- [Pause a pipeline for approval with a Checkpoint](https://mammoth.io/docs/learn/clean-and-shape/checkpoints/): notify people or wait for sign-off.
- [Fix a failing step](https://mammoth.io/docs/learn/clean-and-shape/fix-a-failing-step/): find and fix the task that broke.
- [Activity log and Monitor](https://mammoth.io/docs/learn/automate/activity-log/): where pipeline problems surface.

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Source: https://mammoth.io/docs/learn/clean-and-shape/data-check-failures.md · Updated: 2026-11-08