For the Valuekeep Planner to work correctly, you will need to add a mimeType to your IIS, where the Valuekeep application is installed. – By default, Valuekeep is installed in the “Default Web Site”. To do this, follow the example below, using '.json' as the "File name extension", and 'application/json' as the "MIME type" https://docs.microsoft.com/en-us/iis/configuration/system.webserver/staticcontent/mimemap