Linking OIDC with existing account fails with 500

[achikhv]

Description

Hello!

I tried to add keycloak as authentication source for gitea. I already have users inside gitea, so I added a user with the same email to keycloak's realm.

I configured gitea to use my keycloak as authentication source. Then I was able to login with, and then I got redirected to gitea's link existing account page.

After I provide valid password I get 500 error:

There is a record in logs:

2025/11/21 10:01:12 .../web/auth/linkaccount.go:190:oauth2LinkAccount() [E] UserLinkAccount: mssql: String or binary data would be truncated.

Maybe I can edit database schema manually and increase field size? Will it work, or some fixes in codebase are required?

Gitea Version

1.25.1

Can you reproduce the bug on the Gitea demo site?

No

Log Gist

2025/11/21 10:01:12 .../web/auth/linkaccount.go:190:oauth2LinkAccount() [E] UserLinkAccount: mssql: String or binary data would be truncated.

Screenshots

No response

Git Version

No response

Operating System

Windows server 2019

How are you running Gitea?

Runs as windows service from binary.

Database

MSSQL

[achikhv]

I suppose that the problem is in the external_login_user table. Fields access_token and refresh_token are limited to 255 chars. But keycloak returns JWT's over 1000 chars in length.

So after executing

alter table external_login_user
	alter column refresh_token varchar(MAX) NULL;

alter table external_login_user
	alter column access_token varchar(MAX) NULL;

on gitea's database login was successful.