# studio-missing-slot

> A trigger, condition or action has a required slot left empty.

| | |
| --- | --- |
| Kind | Studio problem |
| Reported by | Studio validation: the Problems panel, Play, Publish and the MCP `validate` tool |
| Code in the Studio | `missing-slot` |

Sentences have holes, called slots. Most slots must be filled before the row can compile; optional ones are marked in the [vocabulary](/reference/studio-events).

An **Any of** with no conditions in it is reported the same way: nothing in it can be true, so its row would never run.

## Fix

- Click the empty slot in the row and fill it in.
- For an empty **Any of**, add a condition to it, or remove it.

## See also

- [Problems and validation](/studio/playtesting)