# BUILDER_RELATION_TARGET_UNKNOWN

A relationship field in `ui-schema.json` names a collection that neither file declares.

## Cause

A relationship field in `ui-schema.json` names a collection that neither file declares.

A relationship or upload field the Schema Builder saved in `ui-schema.json` relates to a collection that neither `ui-schema.json` nor `nextly.config.ts` declares, and that is not `users` or `media`. The Why line lists each field and its target.

## Fix

* Point each field listed at an existing collection, in the Schema Builder or in `ui-schema.json`.
* Or create the collection it names.
* Run `nextly migrate:check` again.

## Example

```text
✗ A field in `ui-schema.json` relates to a collection that does not exist.
  Why:  articles.author relates to unknown target 'authors'
  Next: Point each field listed at a collection in `nextly.config.ts` or `ui-schema.json`, or create the collection it names, then run the command again.
  Docs: https://nextlyhq.com/docs/cli/errors/builder-relation-target-unknown  (BUILDER_RELATION_TARGET_UNKNOWN)
```