When adding an explicit credential to Identity Panel Windows Service (Panel Service) config.json (also used by PanelTools.exe), you may see a 403 connecting to Identity Panel Core Framework (Core) REST API. This may be from lack of permission set in your security token. Restart your web application (Core) and try again.
If you continue to have a 403 error, please search for 403 error in the KB. If you are unable to find your issue, please open a ticket at https://support.identitypanel.com.
See related article: When are explicit credentials needed for Identity Panel Windows Service