30 lines
1,011 B
Markdown
30 lines
1,011 B
Markdown
# Build directory not writeable
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#### Why This Error Occurred
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The filesystem does not allow writing to the specified directory. A common cause for this error is starting a [custom server](https://nextjs.org/docs/advanced-features/custom-server) in development mode on a production server, for example, [Vercel](https://vercel.com) which doesn't allow you to write to the filesystem after your app is built.
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#### Possible Ways to Fix It
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When using a custom server with a server file, for example called `server.js`, make sure you update the scripts key in `package.json` to:
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```json
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{
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"scripts": {
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"dev": "node server.js",
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"build": "next build",
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"start": "NODE_ENV=production node server.js"
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}
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}
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```
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and the custom server starts Next in production mode when `NODE_ENV` is `production`
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```js
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const dev = process.env.NODE_ENV !== 'production'
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const app = next({ dev })
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```
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### Useful Links
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- [Custom Server documentation + examples](https://nextjs.org/docs/advanced-features/custom-server)
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