Error: The response has no "Link" HTTP header.

Hello, It’s my first project using Symfony framework and i’am new with api-platform & admin-on-rest. So for now, i have entities and i build my api with api-platform. Now, i want integrate an admin interface in my project. So i followed the getting starting introduction here https://github.com/api-platform/admin and i replaced entrypoint with my own local api url ‘http://localhost:8000/api/v2’.

1st i was that error : Fetch API cannot load http://localhost:8000/api/v2. Response to preflight request doesn’t pass access control check: The ‘Access-Control-Allow-Origin’ header contains the invalid value ‘null’. Origin ‘http://localhost:3000’ is therefore not allowed access. Have the server send the header with a valid value, or, if an opaque response serves your needs, set the request’s mode to ‘no-cors’ to fetch the resource with CORS disabled.

So i added the nelmio-cors bundle in my project and i added this in my parameter.yml file :

nelmio_cors:
    defaults:
        allow_credentials: false
        allow_origin: []
        allow_headers: []
        allow_methods: []
        expose_headers: []
        max_age: 0
        hosts: []
        origin_regex: false
        forced_allow_origin_value: ~
    paths:
        '^/api/':
            allow_origin: ['*']
            allow_headers: ['X-Custom-Auth', 'Content-Type', 'Link']
            allow_methods: ['POST', 'PUT', 'GET', 'DELETE', 'OPTIONS']
            max_age: 3600
        '^/':
            origin_regex: true
            allow_origin: ['^http://localhost:[0-9]+']
            allow_headers: ['X-Custom-Auth', 'Content-Type', 'Link']
            allow_methods: ['POST', 'PUT', 'GET', 'DELETE', 'OPTIONS']
            max_age: 3600
            hosts: ['^api\.']

After, i have that error:

Uncaught (in promise) Error: The response has no "Link" HTTP header.
    at getDocumentationUrlFromHeaders (parseHydraDocumentation.js:71)
    at parseHydraDocumentation.js:92
    at <anonymous>
         getDocumentationUrlFromHeaders @ parseHydraDocumentation.js:71
         (anonymous) @ parseHydraDocumentation.js:92

How can i fix that ?

[cormack]

Might be a bit late of an answer, but adding the configuration below to nelmio_cors should help you out and anyone else running into this issue.

expose_headers: ["Link"]

[nicolaskern]

This actually is my correct Docker IP. There seems to have an issue with my nginx configuration and Nelmio CORS configuration. When I remove additional headers in nginx, the headers added by Nelmio CORS work fine until I generate a non-200 status.