Umbraco 12. I've got a weird situation where logging in to the backoffice via SSO for one umbraco account returns this message, while other accounts work ok: ArgumentException: An item with the same key has already been added. Key: Umbraco.OpenIdConnect System.Collections.Generic.Dictionary.TryInsert(TKey key, TValue value, InsertionBehavior behavior) System.Collections.Generic.Dictionary.Add(TKey key, TValue value) System.Linq.Enumerable.ToDictionary(List source, Func keySelector, Func elementSelector, IEqualityComparer comparer) System.Linq.Enumerable.ToDictionary(IEnumerable source, Func keySelector, Func elementSelector, IEqualityComparer comparer) System.Linq.Enumerable.ToDictionary(IEnumerable source, Func keySelector, Func elementSelector) Umbraco.Cms.Infrastructure.Persistence.Repositories.Implement.ExternalLoginRepository.Save(Guid userOrMemberKey, IEnumerable tokens) Umbraco.Cms.Core.Services.ExternalLoginService.Save(Guid userOrMemberKey, IEnumerable tokens) Umbraco.Cms.Core.Security.BackOfficeUserStore.UpdateAsync(BackOfficeIdentityUser user, CancellationToken cancellationToken) Microsoft.AspNetCore.Identity.UserManager.UpdateUserAsync(TUser user)... Not sure what to do, can I try deleting the user account? Any ideas? https://docs.umbraco.com/umbraco-cms/reference/security/external-login-providers/