OIDC Authentik not working (Internal Server Error - OAUTH_INVALID_RESPONSE)

[rudstone]

Description

I have trouble to working my OIDC configuration with Authentik provider.

Now, when I try to login in WebAdmin, I have an error during OIDC callback:

{
  "code": 500,
  "error": {
    "name": "Internal Server Error",
    "description": "An unknown error occurred"
  }
}

Container logs (OAUTH_INVALID_RESPONSE) :

d35dff16236d 2026-02-02T14:33:37.824Z [auth] ERROR: Unknown error: ClientError: invalid response encountered
d35dff16236d     at e (file:///app/node_modules/.pnpm/openid-client@6.7.0/node_modules/openid-client/build/index.js:116:12)
d35dff16236d     at errorHandler (file:///app/node_modules/.pnpm/openid-client@6.7.0/node_modules/openid-client/build/index.js:139:23)
d35dff16236d     at Module.authorizationCodeGrant (file:///app/node_modules/.pnpm/openid-client@6.7.0/node_modules/openid-client/build/index.js:953:9)
d35dff16236d     at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
d35dff16236d     at async finishAuthFlow (file:///app/build/server/assets/server-build.js:611:17)
d35dff16236d     at async loader$14 (file:///app/build/server/assets/server-build.js:715:14)
d35dff16236d     at async callRouteHandler (file:///app/node_modules/.pnpm/react-router@7.8.1_react-dom@19.1.1_react@19.1.1__react@19.1.1/node_modules/react-router/dist/development/chunk-IFMMFE4R.mjs:509:16)
d35dff16236d     at async commonRoute.loader (file:///app/node_modules/.pnpm/react-router@7.8.1_react-dom@19.1.1_react@19.1.1__react@19.1.1/node_modules/react-router/dist/development/chunk-IFMMFE4R.mjs:658:19)
d35dff16236d     at async file:///app/node_modules/.pnpm/react-router@7.8.1_react-dom@19.1.1_react@19.1.1__react@19.1.1/node_modules/react-router/dist/development/chunk-UH6JLGW7.mjs:4327:19
d35dff16236d     at async callLoaderOrAction (file:///app/node_modules/.pnpm/react-router@7.8.1_react-dom@19.1.1_react@19.1.1__react@19.1.1/node_modules/react-router/dist/development/chunk-UH6JLGW7.mjs:4379:16) {
d35dff16236d   code: 'OAUTH_INVALID_RESPONSE',
d35dff16236d   [cause]: [OperationProcessingError]
d35dff16236d }

Here is my headplane/config.yaml file :

oidc:
  issuer: "https://sso.example.tld/application/o/headscale/"
  client_id: "XXXXXXXXXXXXXX"
  client_secret: "XXXXXXXXXXXXXX"
  headscale_api_key: "XXXXXXXXXXXXXX"
  disable_api_key_login: true
  token_endpoint_auth_method: client_secret_basic

Headplane Version

0.6.1

Headscale Version

v0.27.1