I want to draw your attention to the T604395: Web - JPEG/JPG images cannot be uploaded to properties of the System.Drawing.Image type

 issue, which is already fixed in XAF v17.2.6. 

We apologize for the inconvenience, and if you cannot wait for the hotfix or did not plan to spend additional time on upgrade right now, please consider using the workarounds.

Important notes and workarounds

From v14.2, Image Property Editors (both WinForms and ASP.NET) support images saved as byte array objects (in addition to previously supported System.Drawing.Image objects). This allows us to significantly decrease web server memory consumption because the byte array can contain an image in a compressed format and the server does not have to unpack it. The previous approach with the System.Drawing.Image type property is still supported, but we recommend that you migrate to the byte array storage to improve performance. Refer to the BLOB Image Properties in XPO  and How to change the image property type from System.Drawing.Image to byte array help topics for more details.