We have got the same problem when some category with "different" jpeg image was loaded. I don't know where is the error or why some picture returns this error. We import pictures directly to DB from ERP so we don't know which image is bad.
We've found the solution. There is some bug in SixLabors.ImageSharp in default version 1.0.0.beta0004 which is included in NopServices and this error was described and solved by developer into version 1.0.0.beta0005. But you have to make small change in PictureService.cs file in Nop.Services/Media.
row (24) commented or removed: using SixLabors.ImageSharp.Processing.Transforms;
row (358) changed: pngEncoder.PngColorType = ... to pngEncoder.ColorType = PngColorType.RgbWithAlpha;
After this change everything works fine. Try it.
Nop Version 4.10