The iisnode module is unable to start the node.exe process. Make sure the node.exe executable is available at the location specified in the <a href=https://github.com/tjanczuk/iisnode/blob/master/src/samples/configuration/web.config>system.webServer/iisnode/@nodeProcessCommandLine</a> element of web.config. By default node.exe is expected in one of the directories listed in the PATH environment variable.