rsnext/errors/circular-structure.mdx

---
title: 'Circular structure in `getInitialProps` result'
---

## Why This Error Occurred

`getInitialProps` is serialized to JSON using `JSON.stringify` and sent to the client side for hydrating the page.

However, the result returned from `getInitialProps` can't be serialized when it has a circular structure.

## Possible Ways to Fix It

Circular structures are not supported, so the way to fix this error is removing the circular structure from the object that is returned from `getInitialProps`.

For example, the `req` instance exposed is a circular object and can not be serialized, instead the specific fields such as relevant headers on the instance should be passed specifically.
docs: Migrate error messages to MDX and App Router. (#52038) This PR is part of a larger effort to migrate error messages to MDX and use App Router: https://github.com/vercel/front/pull/23459 2023-07-05 15:11:16 +02:00			`---`
			title: 'Circular structure in `getInitialProps` result'
			`---`
Implement circular JSON err.sh link (#6149) * Implement circular JSON err.sh link * Add test for getInitialProps returning circular json * Make test warn less * Fix tests * Add reference to original tests 2019-01-27 16:12:17 +01:00
docs: Migrate error messages to MDX and App Router. (#52038) This PR is part of a larger effort to migrate error messages to MDX and use App Router: https://github.com/vercel/front/pull/23459 2023-07-05 15:11:16 +02:00			`## Why This Error Occurred`
Implement circular JSON err.sh link (#6149) * Implement circular JSON err.sh link * Add test for getInitialProps returning circular json * Make test warn less * Fix tests * Add reference to original tests 2019-01-27 16:12:17 +01:00
Remove trailing spaces (#6547) ### changes #### remove trailing spaces When I was using example I noticed trailing spaces. So, this PR removes the trailing spaces of json file, README, and others. `examples/with-jest-typescript/src/modules/cars/Overview.tsx` also has it, but this time it did not change as tslint error occurs at commit. 2019-03-07 17:40:08 +01:00			`getInitialProps` is serialized to JSON using `JSON.stringify` and sent to the client side for hydrating the page.
Implement circular JSON err.sh link (#6149) * Implement circular JSON err.sh link * Add test for getInitialProps returning circular json * Make test warn less * Fix tests * Add reference to original tests 2019-01-27 16:12:17 +01:00
			However, the result returned from `getInitialProps` can't be serialized when it has a circular structure.

docs: Migrate error messages to MDX and App Router. (#52038) This PR is part of a larger effort to migrate error messages to MDX and use App Router: https://github.com/vercel/front/pull/23459 2023-07-05 15:11:16 +02:00			`## Possible Ways to Fix It`
Implement circular JSON err.sh link (#6149) * Implement circular JSON err.sh link * Add test for getInitialProps returning circular json * Make test warn less * Fix tests * Add reference to original tests 2019-01-27 16:12:17 +01:00
			Circular structures are not supported, so the way to fix this error is removing the circular structure from the object that is returned from `getInitialProps`.
Add note about req to circular-structure error doc (#47162) Co-authored-by: JJ Kasper <22380829+ijjk@users.noreply.github.com> 2023-03-27 05:44:31 +02:00
			For example, the `req` instance exposed is a circular object and can not be serialized, instead the specific fields such as relevant headers on the instance should be passed specifically.