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# Fix a pending batch or schema mismatch in Mammoth

> Resolve a Mammoth batch that says Pending or Schema mismatch: map incoming columns, check how the file was read, and apply the mapping to similar files.
>
> Applies to: Where: Data Library › dataset panel › Settings & history › Batches › pending batch

After you add a file to a dataset, its batch reads **Applying recipe** while Mammoth structures it, or **Pending** when it needs your input: a column mapping, a sheet selection or a file password. Find it in the dataset's panel under **Settings & history** > **Batches** and select it to resolve it. See [Batches: see, suspend and fix what arrived](https://mammoth.io/docs/learn/get-data-in/batches/) for the batch list.

## Applying recipe: no action needed

"This batch is messy data being automatically structured using your saved recipe." No action is needed, and it finishes shortly.

## Open a pending batch's settings

Select a pending batch to open its settings, titled with the file name, such as **Settings - June_Sales_Combined.csv**. A batch whose columns don't line up with the dataset is marked "Schema mismatch: column mapping required".

| Tab | What it does |
| --- | --- |
| **Column Mapping** | Matches each **Incoming** column to a **Destination** column. The header says how many matched (for example, "9 of 11 columns matched by name.") and how many need you. Columns are split into **Mapped** and **Unmapped**. A suggestion names the column, such as **Looks like Region**, with why (**same words**, or **same words, same type**). Use **Unmap** to undo a match, or **Ignore this column** to leave a column out. |
| **Data** | How the file was read: **Delimiter**, **Column headers**, **Initial rows to skip** and the date format, plus any rows that didn't fit, with **Discard all** and **Restore all** |

## What ignoring a column costs

Mammoth tells you, for example "Store ID will not be added" for an incoming column, or "Region will be empty for these rows. Existing rows keep theirs." for a destination column. If nothing lines up, Mammoth warns that the file was probably sent to the wrong dataset.

## Apply the mapping to similar files

1. When other pending files have the same columns, tick **Also apply to** the other files (for example, **Also apply to 2 other files with these columns**).
2. Click **Apply changes**.

Mammoth adds them all with this mapping and saves it, so files like this go in on their own next time ("Saved to How new files are added. Files like this will go in from now on."). To set mapping rules before a file arrives, see [Set column mapping and type rules](https://mammoth.io/docs/learn/get-data-in/column-mapping-rules/).

## Related

- [Batches: see, suspend and fix what arrived](https://mammoth.io/docs/learn/get-data-in/batches/): the batch list and troubleshooting.
- [Set column mapping and type rules](https://mammoth.io/docs/learn/get-data-in/column-mapping-rules/): aliases and type rules for every new file.
- [Add or replace data in a dataset](https://mammoth.io/docs/learn/get-data-in/add-or-replace-data/): where new batches come from.
- [Review how Mammoth reads a file](https://mammoth.io/docs/learn/get-data-in/how-mammoth-reads-files/): delimiters, headers and recipes.

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Source: https://mammoth.io/docs/learn/get-data-in/pending-batches.md · Updated: 2026-11-08