haven't seen this error. we do have .svg files and they show up ok. what's markup in preview for you?

Is this of any help: https://world.episerver.com/blogs/Ben-McKernan/Dates/2015/7/supporting-svg-images/ ?

In the end I solved it by adding svg to the ImageFile Content Type

[ContentType(DisplayName = "Image", GUID = "79a4e457-e026-4ce7-a5a7-37893e2b0db8", Description = "")]
[MediaDescriptor(ExtensionString = "jpg,jpeg,png,gif,svg")]
public class ImageFile : ImageData
{
[CultureSpecific]
[Editable(true)]
[Display(
Name = "Alternate text",
Description = "Description of the image",
GroupName = SystemTabNames.Content,
Order = 1)]
public virtual String Description { get; set; }

public override Blob Thumbnail
{
get { return BinaryData; }
}
}

Hi Ayo, I'd encourage you to create a new Class for your SVG rather than adding it to the ImageFile.

The reason is if you override Thumbnail in your current ImageFile class its going to return the original Binary data for all your Images including jpg, jpeg, png, gif. If these are large, you'll be slowing down your CMS.

Consider this instead...

    [ContentType(DisplayName = "VectorImageFile", GUID = "c0b70fd0-0d5b-4c53-83fe-e32ea8faa2d5", Description = "")]
    [MediaDescriptor(ExtensionString = "svg")]
    public class VectorImageFile : ImageFile
    {
        /// <summary>
        /// Gets the generated thumbnail for this media.
        /// </summary>
        public override Blob Thumbnail
        {
            get { return BinaryData; }
        }
    }

I've written a blog on this recently if you want to check that out... https://www.luminary.com/blog/image-metadata-svg-thumbnails-episerver-dxc

I saw your blog Darren, and it is a nice solution