# 19043: Field definition name already exists

Log Type: APPLICATION

Log Level: ERROR

## Description

This error is returned when a request attempts to create or rename a custom field definition to a `name` that is already present for the account. Field definition names must be unique. Field definition `name` values are enforced as case-insensitively unique in the SendGrid Marketing Campaigns API, which manages custom field definitions.

### Possible causes

* The `name` supplied in `POST /v3/marketing/field_definitions` matches (case-insensitively) an existing custom field definition.
* An update via `PATCH /v3/marketing/field_definitions/{custom_field_id}` attempts to change `name` to one that already exists.

### Possible solutions

* Choose a unique `name` value; uniqueness is case-insensitive, so avoid names that differ only by letter case.
* List existing definitions first with `GET /v3/marketing/field_definitions` and verify that the desired `name` is not already present (including case-insensitive matches).
* If you intended to modify an existing definition, update it using `PATCH /v3/marketing/field_definitions/{custom_field_id}` rather than creating a new one.
* If you must replace an existing definition, remove it with `DELETE /v3/marketing/field_definitions/{custom_field_id}` before creating a new one (only custom fields can be deleted).

#### Additional resources

* [Create Custom Field Definition](/docs/sendgrid/api-reference/custom-fields/create-custom-field-definition)
* [Get All Field Definitions](/docs/sendgrid/api-reference/custom-fields/get-all-field-definitions)
* [Update Custom Field Definition](/docs/sendgrid/api-reference/custom-fields/update-custom-field-definition)