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Area

authentication

Describe the bug

We’re encountering an issue when two tabs are open:

In the first tab, the user is correctly authenticated with Client A.

In the second tab, additional validation is required to authenticate with Client B, which is expected behavior.

However, due to the multiple open tabs, Keycloak treats the second authentication as part of the OpenID Connect flow. When we try to change the language during this flow, Keycloak throws the following error:

2025-07-18 12:37:24,378 ERROR [org.keycloak.services] (executor-thread-165) KC-SERVICES0092: Missing parameter: response_type

The issue seems to be with the locale URL provided by Keycloak. Initially, it includes the correct response_type parameter, as shown here:

http://localhost:8080/realms/sqin/protocol/openid-connect/auth?client_id=some_client&redirect_uri=some_redirect_uri&response_type=code&scope=openid[...]

However, a subsequent redirection happens to another URL, and this second request is missing the response_type parameter:

http://localhost:8080/realms/sqin/protocol/openid-connect/auth?client_id=some_client&tab_id=oyan_6PBsJI&client_data=some_token&execution=89232e7c-cf9b-41d7-bbaf-48f5edbda730&kc_locale=en

Please note that when performing a regular login (login-actions) on a single tab without another client authenticated, Client B locale translation works as expected.

Version

26.1.3

Regression

• The issue is a regression

Expected behavior

The response_type should be passed inside the locale redirection url in the openid-connect authorization flow.

Actual behavior

The response_type is not included inside the locale redirection url, which is throwing errors and cancelling the translation.

How to Reproduce?

Create client A and client B.

• Add a different level of authentication (ACR) validation to client B, using a flow step that prevents SSO from automatically logging into client B after the user logs into client A.
• Log in to client A.
• Start the authentication flow for client B in a second tab. You will see the validation step in the OpenID Connect flow.
• Try changing the language during the validation step in client B.

Anything else?

No response