Hi,

I think, in this case, we need to create a custom event handler, which will automatically reorder the media items whenever new media is uploaded or saved.

For example:

using Umbraco.Cms.Core.Events;
using Umbraco.Cms.Core.Notifications;
using Umbraco.Cms.Core.Services;
using Umbraco.Cms.Core.Web;

public class MediaSavedEventHandler : INotificationHandler<MediaSavedNotification>
{
    private readonly IMediaService _mediaService;

    public MediaSavedEventHandler(IMediaService mediaService)
    {
        _mediaService = mediaService;
    }

    public void Handle(MediaSavedNotification notification)
    {
        foreach (var media in notification.SavedEntities)
        {
            if (media.ParentId > 0) // Ensure the media is inside a folder
            {
                var siblings = _mediaService.GetPagedChildren(media.ParentId, 0, int.MaxValue, out _)
                                            .OrderByDescending(m => m.CreateDate); // Sort by creation date, descending

                int sortOrder = 0;
                foreach (var sibling in siblings)
                {
                    if (sibling.SortOrder != sortOrder)
                    {
                        sibling.SortOrder = sortOrder;
                        _mediaService.Save(sibling); // Save without triggering events
                    }
                    sortOrder++;
                }
            }
        }
    }
}

Then register the event handler in the Startup.cs file or the Program.cs.

Example for registering the event handler in Program.cs

builder.Services.AddUmbraco(builder.Configuration)
    .AddBackOffice()
    .AddWebsite()
    .AddComposers()
    .AddNotificationHandler<MediaSavedNotification, MediaSavedEventHandler>() // Register the event handler
    .Build();

FYI: I got the above solution from ChatGPT.

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