Docker not found/working

Hi guys, I ran it from root.

When I tried to rebuild the app, this is the error presented:

root@forum:/var/discourse# ./launcher rebuild app
/usr/bin/docker: Error response from daemon: OCI runtime create failed: container_linux.go:348: starting container process caused "process_linux.go:297: copying bootstrap data to pipe caused \"write init-p: broken pipe\"": unknown.
Your Docker installation is not working correctly

See: https://meta.discourse.org/t/docker-error-on-bootstrap/13657/18?u=sam
root@forum:/var/discourse# 

I have tried to remove the docker and then reinstalling it. Same error message as above.
Any help would be appreciated.