---
title: "NUXT_B5003"
description: "Reserved runtimeConfig.app namespace"
canonical_url: "https://nuxt.com/docs/4.x/errors/b5003"
---
# B5003

You have custom keys under `runtimeConfig.app`, a namespace Nuxt reserves for internal values (such as `baseURL` and `cdnURL`). Custom keys here can collide with Nuxt's own config.

## Resolution

Move custom keys to `runtimeConfig.public` (exposed to the client) or to a top-level custom namespace (server-only):

```ts
export default defineNuxtConfig({
  runtimeConfig: {
    // instead of runtimeConfig.app.myKey
    public: {
      myKey: 'value',
    },
  },
})
```

<read-more to="https://nuxt.com/docs/4.x/guide/going-further/runtime-config">



</read-more>


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