---
title: "NUXT_B5001"
description: "Missing compatibilityDate"
canonical_url: "https://nuxt.com/docs/4.x/errors/b5001"
---
# B5001

No `compatibilityDate` is set in your Nuxt configuration. Nuxt uses this date to decide which behaviour defaults to apply, so your project stays stable across Nuxt and Nitro updates instead of silently picking up new defaults.

## Resolution

Add `compatibilityDate` to your `nuxt.config`, using today's date so you opt in to the current defaults:

```ts
export default defineNuxtConfig({
  // use the current date, e.g. the day you add this line
  compatibilityDate: 'YYYY-MM-DD',
})
```

<read-more to="https://nuxt.com/docs/4.x/getting-started/upgrade">



</read-more>


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