marco.salviUpgrading from a previous version of ImageResizer? You may need to correct your Web.config file. If you see 2 duplicate elements like the following, remove the shorter one. <section name="resizer" type="ImageResizer.ResizerSection"/> <section name="resizer" type="ImageResizer.ResizerSection" requirePermission="false"/> You can find the release changelog at http://imageresizing.net/releases