Kong Manager admin login fails when the casing of the email address doesn't match what's stored in Kong

We are using openid-connect authentication with Kong Manager, and admins have had problems logging into Kong when the email address that was used to log in differs in terms of casing from what was created when the admin was created initially in Kong.

The kong logs show the following:

2026/09/07 08:31:41 [debug] 2072#0: *4289703 [lua] api_helpers.lua:141: validate_admin(): [api_helpers] Admin not found with user_name=Firstame.Lastname@mycompnay.com

But the Admin username in Kong is firstname.lastname@mycompany.com

How can we make sure that email addresses to log into Manager are NOT case sensitive.

The openid-connect plugin has a property, i.e. by_username_ignore_case, which allows username values to be matched case-insensitively with Identity Provider claims. It is possible to match usernames case-insensitively by adding "by_username_ignore_case": true to the existing admin_gui_auth_conf configuration option used by Kong Manager as in the example in this KB article.