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# Fix column type and formula errors in a pipeline

> Fix Mammoth pipeline tasks that fail on the wrong column type or a bad Math Function expression: text numbers, text dates and every formula message.
>
> Applies to: Where: View › Pipeline › failing task › Fix error

A task fails with a type error when it gets a column it can't handle, such as text where it needs a number. A Math Function fails when its expression is incomplete or names a column that isn't there. Click **Fix error** on the red task card, then use the fixes below. For the general steps, see [Fix a failing step](https://mammoth.io/docs/learn/clean-and-shape/fix-a-failing-step/).

## Fix column type problems

The task got a type it can't handle: arithmetic on text, or a date step on text. Typical causes are dates imported as text (sorting, filtering and totals go wrong), a number column holding text such as `N/A`, or a calculation on a column not yet converted.

1. Check the column's type in the failing task.
2. Add a **Convert Column Type** task before it, converting to the type the task needs. Clean text first (remove symbols, deal with non-numeric values).

![Convert Column Type panel with a text column selected, the Date type chosen, Format Output set to Universal, and the date format list open showing YYYY/MM/DD and YYYY-MM-DD options](https://mammoth.io/docs/images/20261009_100706_ConvertColumnTypeDateFormat.webp)

**Dates in mixed formats** come from different systems, are treated as text, sort wrongly, and include invalid values such as `2024-13-01` or `Feb 30 2024`. Check the type and the Data Quality report, see the mix of formats with Explore cards, then add **Convert Column Type** with **Format Output** (Universal, UK, US or Custom) set to match. Test it with Draft mode or **Preview Data at this Task**. Better still, standardise the format at the source or check it at the start of the pipeline. See [Convert text to dates and numbers](https://mammoth.io/docs/learn/clean-and-shape/convert-column-type/).

## Fix Math Function expression errors

The expression editor says what is wrong:

| Message | What to check |
| --- | --- |
| "Column Revenue is missing" | The column doesn't exist at this step. Check spelling, and columns renamed or removed earlier. |
| "not a numeric column" or "Only numeric columns allowed" | A column is text or a date. Convert it with **Convert Column Type** first. |
| "Empty expression" | Enter an expression |
| "Syntax error: unmatched brackets" | Close every opening bracket |
| "Expected an operator +, -, *, / before Discount" | Two values or columns sit side by side with no operator |
| "Expression can not begin with * or /" or "Expression can not end with any of +, -, *, /" | Add the missing value at the start or end |
| "Invalid arguments for SUM" or "Function SUM takes exactly 1 argument" | Give the function one column name in double quotes, for example `SUM("Revenue")`. See [Calculate with formulas](https://mammoth.io/docs/learn/clean-and-shape/formulas/). |

Division by zero depends on your data. If a divisor can be zero, filter those rows out first with a **Conditional Filter**, or handle them in a separate flow.

## Related

- [Fix a failing step](https://mammoth.io/docs/learn/clean-and-shape/fix-a-failing-step/): find the first failing task and fix or delete it.
- [Convert text to dates and numbers](https://mammoth.io/docs/learn/clean-and-shape/convert-column-type/): every Convert Column Type option.
- [Error messages](https://mammoth.io/docs/learn/help/errors/): every error message in one place.

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Source: https://mammoth.io/docs/learn/clean-and-shape/fix-type-and-formula-errors.md · Updated: 2026-11-08