Systemd enabled services not starting at boot anymore - linux

Question

I made some custom systemd services long time ago, all have the same configuration (except for the ExecStart of course)
This configuration worked for years, I have ubuntu up and running since version 18.04 LTS, but now looks like some of these systemd services aren't starting at boot at all, the configuration is as follow (myapp.service):
[Unit]
Description="myapp"
After=syslog.target network-online.target
Wants=network-online.target
[Service]
Restart=always
RestartSec=10
User=root
Group=root
WorkingDirectory=/opt/myapp
ExecStart=/usr/local/bin/myapp
KillMode=control-group
[Install]
WantedBy=multi-user.target
The service is enabled:
$ sudo systemctl enable myapp
Created symlink /etc/systemd/system/multi-user.target.wants/myapp.service → /lib/systemd/system/myapp.service.
If i do "systemctl status myapp" after a reboot:
● myapp.service - "myapp"
Loaded: loaded (/lib/systemd/system/myapp.service; enabled; vendor preset: enabled)
Active: inactive (dead)
If i do "journalctl -u myapp -f" after a reboot:
Jan 13 12:10:06 myhost systemd[1]: Started myapp.
Jan 17 07:15:03 myhost systemd[1]: Stopping myapp...
Jan 17 07:15:09 myhost systemd[1]: Stopped myapp.
What's wrong with my configuration?
If I manually start /usr/local/bin/myapp there are no errors on the script and I've also tried running it with tmux, now it's 3 days running in bg and no errors. But systemd just won't start it after a reboot.
Today, i've also tried to install a new service that require a systemd config, the package is zram-config and by default it is enabled at boot.
But after a: apt install zram-config && sudo reboot:
$ sudo systemctl status zram-config
● zram-config.service - Initializes zram swaping
Loaded: loaded (/lib/systemd/system/zram-config.service; enabled; vendor preset: enabled)
Active: inactive (dead)
but if now i do:
$ sudo systemctl start zram-config
$ sudo systemctl status zram-config
● zram-config.service - Initializes zram swaping
Loaded: loaded (/lib/systemd/system/zram-config.service; enabled; vendor preset: enabled)
Active: active (exited) since Mon 2020-01-27 12:25:55 CET; 1s ago
Process: 5541 ExecStart=/usr/bin/init-zram-swapping (code=exited, status=0/SUCCESS)
Main PID: 5541 (code=exited, status=0/SUCCESS)
Jan 27 12:25:55 myhost systemd[1]: Starting Initializes zram swaping...
Jan 27 12:25:55 myhost init-zram-swapping[5541]: Setting up swapspace version 1, size = 985,7 MiB (1033568256 bytes)
Jan 27 12:25:55 myhost init-zram-swapping[5541]: nessuna etichetta, UUID=4ac5c2cd-0c68-4f6d-a5c0-d8f91a509c71
Jan 27 12:25:55 myhost init-zram-swapping[5541]: Setting up swapspace version 1, size = 985,7 MiB (1033568256 bytes)
Jan 27 12:25:55 myhost init-zram-swapping[5541]: nessuna etichetta, UUID=83a4f201-d591-4222-89a6-5bc5aebedef4
Jan 27 12:25:55 myhost init-zram-swapping[5541]: Setting up swapspace version 1, size = 985,7 MiB (1033568256 bytes)
Jan 27 12:25:55 myhost init-zram-swapping[5541]: nessuna etichetta, UUID=1f6f742e-6fb8-4332-b226-bf6918f7ee28
Jan 27 12:25:55 myhost init-zram-swapping[5541]: Setting up swapspace version 1, size = 985,7 MiB (1033568256 bytes)
Jan 27 12:25:55 myhost init-zram-swapping[5541]: nessuna etichetta, UUID=a5509c55-46f5-4112-8fe1-68171f31409e
Jan 27 12:25:55 myhost systemd[1]: Started Initializes zram swaping.
I really don't understand what's wrong with systemd on my Ubuntu install, is it better I do a fresh reinstall of whole OS?
Thanks

Answer 1

Check the full output of journalctl for a message about cycles, like:
Job <your.service> deleted to break ordering cycle starting with <something else>
I had the similar issue. It was due to ordering cycles, which was very hard to debug and fix.