Docker container with ShinyProxy – "message":"No command specified"

Hi I followed the steps from this tutorial: https://lukesingham.com/shiny-containers-with-shinyproxy/.

When running the Euler App outside of ShinyProxy with:

 sudo docker run -p 3838:3838 openanalytics/shinyproxy-template R -e 'shinyproxy::runApp("/root/euler")'

Everything is working correctly. The Problem starts when trying to access it from ShinyProxy. Then I get the following Error message:

Error
Status code: 500

Message: Failed to start container

Caused by: com.spotify.docker.client.exceptions.DockerRequestException: Request error: POST 
http://localhost:2375/containers/create: 400, body: {"message":"No command specified"}

The Hello-world app and the 06_tabsets app is working correctly outside and inside of ShinyProxy!

I am hosting it on a Azure VM (Ubuntu 16.04). Docker version 18.09.7. Let me know if you need some more Information let me know.

Thanks in advance for any help!

Source: StackOverflow