Unable to update item with ISession

[weirdyang]

I'm trying to update an item with ISession, here's my code

            _session.Save(profile, MqttProfile.Collection);
            await _session.SaveChangesAsync();

But it always throws this error

I don't get it, what is wrong with my update method?

I found an issue which said to avoid Task.WhenAll, but I am not using that method in my code.

        public async Task<Result<MqttProfile>> SaveMqttProfile(MqttProfile profile)
        {
            var isDuplicate = await GetMqttProfileByNameAndClientId(profile.ClientName, profile.ClientId);
            if (isDuplicate.Success && isDuplicate.Value is not null)
            {
                return new Result<MqttProfile>(profile, "Client name and client id needs to be unique")
                {
                    Exception = new ArgumentException("Duplicate client name or client id")
                };
            }

            bool isNew = profile.Id == 0;
            Result<MqttProfile>? oldProfile = null;
            if (!isNew)
            {
                oldProfile = await GetMqttProfileByDocumentId(profile.Id);
                if (!oldProfile.Success && oldProfile.Value is null)
                {
                    isNew = true;
                }
            }

            _session.Save(profile, MqttProfile.Collection);
            await _session.SaveChangesAsync();
            if (isNew)
            {
                await _createdHandlers.InvokeAsync(async x => await x.HandleCreate(profile), _logger);
            }
            else
            {
                await _updatedHandlers.InvokeAsync(async x => await x.HandleUpdate(profile, oldProfile!.Value!), _logger);
            }

            return new Result<MqttProfile>(profile);
        }

[weirdyang]

so the issue was running these two operations before I called save:

            var isDuplicate = await GetMqttProfileByNameAndClientId(profile.ClientName, profile.ClientId);
            if (isDuplicate.Success && isDuplicate.Value is not null)
            {
                return new Result<MqttProfile>(profile, "Client name and client id needs to be unique")
                {
                    Exception = new ArgumentException("Duplicate client name or client id")
                };
            }

            bool isNew = profile.Id == 0;
            Result<MqttProfile>? oldProfile = null;
            if (!isNew)
            {
                oldProfile = await GetMqttProfileByDocumentId(profile.Id);
                if (!oldProfile.Success && oldProfile.Value is null)
                {
                    isNew = true;
                }
            }

But how do i check for duplicated names?