Cannot Start Docker Daemon (Graphdriver Issue)

running Ubuntu 16.04.5 LTS 4.4.0-108-generic on a virtual private server My aim is to deploy a meteor application with mup.js, but it fails because of dockerd not being launched. The problem is, i cannot get dockerd to launch after a system reboot.

I tried changing graphdriver as suggested in other threads (Not able to start docker on Ubuntu 16.04.2 LTS (error initializing graphdriver)), switching to aufs or overlay2, but to no avail. I also updated my kernel, purged docker repos, reinstalled docker on my machine.

i have close to no experience working with docker, and the website i'm trying to put back online is part of a show, the last night of which is tomorrow! i must say i'm getting a bit desperate, any help is welcome.

thank you!

docker & dockerd are both version 18.06.1-ce, build e68fc7a

$ sudo dockerd

INFO[0000] libcontainerd: new containerd process, pid: 3488 
WARN[0000] containerd: low RLIMIT_NOFILE changing to max  current=1024 max=1048576
WARN[0000] failed to rename /var/lib/docker/tmp for background deletion: %!s(<nil>). Deleting synchronously 
Error starting daemon: error initializing graphdriver: driver not supported

journalctl -xe yields :

Oct 03 01:22:19 vps332343 systemd[1]: Listening on Docker Socket for the API.
-- Subject: Unit docker.socket has finished start-up
-- Defined-By: systemd
-- Support: 
-- 
-- Unit docker.socket has finished starting up.
-- 
-- The start-up result is done.
Oct 03 01:22:19 vps332343 systemd[1]: docker.service: Start request repeated too quickly.
Oct 03 01:22:19 vps332343 systemd[1]: Failed to start Docker Application Container Engine.
-- Subject: Unit docker.service has failed
-- Defined-By: systemd
-- Support: 
-- 
-- Unit docker.service has failed.
-- 
-- The result is failed.
Oct 03 01:22:19 vps332343 systemd[1]: docker.socket: Unit entered failed state.
Oct 03 01:22:37 vps332343 sudo[3651]:  eboutin : TTY=pts/0 ; PWD=/etc/nginx/sites-available ; USER=root ; COMMAND=/bin/journalctl -xe
Oct 03 01:22:37 vps332343 sudo[3651]: pam_unix(sudo:session): session opened for user root by eboutin(uid=0)

df -tH yields :

Filesystem     Type      Size  Used Avail Use% Mounted on
udev           devtmpfs  970M     0  970M   0% /dev
tmpfs          tmpfs     196M  5.6M  190M   3% /run
/dev/vda1      ext4      9.7G  4.6G  5.1G  48% /
copymods       tmpfs     977M   28K  977M   1% /lib/modules
tmpfs          tmpfs     977M   68K  977M   1% /dev/shm
tmpfs          tmpfs     5.0M     0  5.0M   0% /run/lock
tmpfs          tmpfs     977M     0  977M   0% /sys/fs/cgroup
tmpfs          tmpfs     196M     0  196M   0% /run/user/1002
tmpfs          tmpfs     196M     0  196M   0% /run/user/1001

/etc/docker/daemon.json contents :

{"storage-driver":"devicemapper"}

(no other modified config file)