Это пипец (только слово похожее). Ответ от саппорта.
I understand that you are getting error if you try to edit it and save it, the reason for this is because username in salesforce must be unique across all Salesforce orgs, including trial and Sandbox orgs. The email used for the username need not function or match the email address used for the account.
You have created this user in 2020 and I can see that this is the user that you are trying to edit . However there exists another partner user record of this user with same one at the backend which is causing the issue . Could you please check with the user to see if he has been using his email with any other partners?Ну и что это означает????? Какие partners????
Вот весь ИИ в действии!!!! А мы еще радуемся что скоро ИИ заменит людей!!!