Hacktoberfest 2026: the issues maintainers tagged for October, open and beginner-friendly. Browse Hacktoberfest issues

Docs error after upgrading to API Platform v4.0.2 (backend) and API Platform Admin v4.0.1 (frontend)

Open
#583 6 comments 2 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Stale
Tech stack
react, typescript
Domain
api, frontend

Research direction

Reproduce the failure with API Platform v4.0.2 on the backend and API Platform Admin v4.0.1 on the frontend, then compare it with the working v3.3.7 backend combination. Inspect the API documentation response and the frontend documentation fetch path; done means the latest backend and frontend load the API documentation without the supportedClass error.

Written by the indexing model from the issue text.

Description

Hi API Platform Admin Team,

I was previously using API Platform v3.3.7 for my backend and API Platform Admin v3.4.7 for my frontend.
After upgrading to API Platform v4.0.2 and API Platform Admin v4.0.1, I encountered the following error on the frontend :

Cannot fetch API documentation:
The API documentation has no "http://www.w3.org/ns/hydra/core#supportedClass" key or its value is not an array.
Have you verified that CORS is correctly configured in your API ?

The hydra-prefixed tags have been removed from my APIs as expected, but the API responses are otherwise in the correct format.

Interestingly, if I revert the backend to API Platform v3.3.7 while keeping the frontend at API Platform Admin v4.0.1, everything works fine. The issue only appears when both the backend and frontend are on the latest versions (v4.x).

Thank you for your help!

Dominant language
TypeScript
Stars
516
Forks
134
PR merge metrics
No merged PRs in 30d

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

More from api-platform/admin

All issues in api-platform/admin

Similar issues

More TypeScript issues

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.