This should be the Error UI
You ended up here because you didn't set the following configuration value:
"path/to/kratos/config.yml
selfservice:
flows:
error:
ui_url: http://my-app.com/error
You can set this configuration value using environment variable SELFSERVICE_FLOWS_ERROR_UI_URL
as well!
If you don't know what that means, head over to User-Facing Error!