---
title: "NUXT_E7010"
description: "callOnce key must be a string."
canonical_url: "https://nuxt.com/docs/4.x/errors/e7010"
---
# E7010

`callOnce()` was called with a key that is not a string. The key is used to track whether the function has already run, so it must be a non-empty string.

## Resolution

```ts
await callOnce('setup', () => {
  // runs once
})
```

::read-more{to="https://nuxt.com/docs/4.x/api/utils/call-once"}
::


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