Auth0 Support Center - LinkedIn Social Connection - "locale" Claim is an Object Instead of a String

LinkedIn Social Connection - "locale" Claim is an Object Instead of a String

Sep 10, 2025

Overview

While the Open ID Connect (OIDC) specs state the "locale" claim as a string:

https://openid.net/specs/openid-connect-core-1_0.html#StandardClaims:~:text=America/Los_Angeles.-,locale,string,-End%2DUser%27s%20locale

LinkedIn returns an object as a value for that attribute, and Auth0 also takes it as an object in the normalized user profile.

This document proposes a solution to pass a flattened "locale" attribute in the token using Actions.

Applies To

LinkedIn Social Connection
"locale" claim

Cause

LinkedIn is returning the ID Token with the "locale" claim in an object format instead of a string.

This is the ID Token from LinkedIn:

  "sub": "linkedin|Gxxxxx",

  "given_name": "<First Name>",

  "family_name": "<Last Name>",

  "nickname": "<Nickname>",

  "name": "<Full Name>",

...

  "locale": {

    "country": "ES",

    "language": "es"

},

  "updated_at": "2025-07-02T15:31:58.178Z",

  "iss": "https://<domain>.auth0.com/",

  "aud": "<aud>",

  "iat": 1751470394,

  "exp": 1751506394,

  "sid": "<sid>",

...

Auth0 is taking that claim and storing it in the user profile as an object:

{
"created_at": "2025-07-01T23:40:19.372Z",
"family_name": "<Last Name>",
"given_name": "<First Name>",
"identities": [
{
"provider": "linkedin",
"user_id": "Gxxxxxxx",
"connection": "linkedin",
"isSocial": true
}
],
"locale": {
"country": "ES",
"language": "es"
},
"name": "<Full Name>",
"nickname": "<Nickname>",
...
"sub": "xxxz",
"updated_at": "2025-07-02T15:55:57.034Z",
"user_id": "linkedin|Gxxxxxxx",
"last_ip": "<IP Address>",
"last_login": "2025-07-02T15:55:57.033Z",
"logins_count": 9,
"blocked_for": [],
"guardian_authenticators": [],
"passkeys": []
}

Solution

Create a Post Login Action to flatten the locale scope and then add it to a custom claim on the IDToken:

/**
* Flatten the locale scope if it's not a string
*/
exports.onExecutePostLogin = async (event, api) => {
const { locale } = event.user;
if (typeof locale === "object") {
// linkedin sets the locale as an object like this:
// "locale": {
// "country": "US",
// "language": "en"
//},

// flatten the locale:
api.idToken.setCustomClaim(
"locale",
`${locale.language}-${locale.country}`
);
}
};

See Create custom claims for more details on setting custom claims with Actions.