DFS 10.4.0 - AssetNotFound image placeholder

The DAM for Sitecore media pipeline that serves the media (DFS 10.4.0 - 9 Serving media), has a fallback feature. If it cannot serve the requested image it will show a placeholder image insted. The image that is shown is configured in this files \App_Config\Include\damforsitecore\DFS.Services.config. Look for these settings:

<setting name="DFS.Services.AssetNotFoundImage.MimeType" value="image/jpg" />
<setting name="DFS.Services.AssetNotFoundImage.Path" value="/App_Data/AssetNotFound.jpg" />  

Rendering of DFS fieldtypes

The rendering of the DFS fieldtypes will generate the html tag for that page (DFS 10.4.0 - 3 Render DAM for Sitecore Field Types). If the rendering cannot access or find the requeated asset, it will genereate a fallback html tag like this <img src='/dfsmedia/notfoundAsset' alt='Not Found' />. Out of the box, this url will genereate a 500 internal server error. In order to fix this and have the site render an placeholder image. You have to add a handler to your web.config file. Navigate to the section "/configuration/system.webServer/handlers" and add the following handler.

<add name="DFSNotFound" verb="GET" path="dfsmedia/notfoundAsset" type="DFS.Services.Handlers.DfsNotFoundMediaHandler" />

Now the url will show the placeholder image.