Version: 7.6.31 x86_64-pc-linux-gnu

I have edited the file /lib/systemd/system/boinc-client.service to use the directory 'boinc_data' on my home:

[Unit]
Description=Berkeley Open Infrastructure Network Computing Client
After=network.target

[Service]
Nice=10
User=boinc
PermissionsStartOnly=yes
ExecStartPre=/usr/bin/touch /home/aubin/boinc_data/boinc.log /home/aubin/boinc_data/boincerr.log
ExecStartPre=/bin/chown boinc:boinc /home/aubin/boinc_data/boinc.log /home/aubin/boinc_data/boincerr.log
ExecStart=/bin/sh -c '/usr/bin/boinc --dir /home/aubin/boinc_data >/home/aubin/boinc_data/boinc.log 2>/home/aubin/boinc_data/boincerr.log'
ExecReload=/usr/bin/boinccmd --read_cc_config
ExecStopPost=/bin/rm -f /home/aubin/boinc_data/lockfile
IOSchedulingClass=idle

[Install]
WantedBy=multi-user.target

sudo service boinc-client status
● boinc-client.service - Berkeley Open Infrastructure Network Computing Client
   Loaded: loaded (/lib/systemd/system/boinc-client.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since jeu. 2017-11-30 21:16:15 CET; 17min ago
  Process: 29044 ExecStopPost=/bin/rm -f /home/aubin/boinc_data/lockfile (code=exited, status=0/SUCCESS)
  Process: 29042 ExecStart=/bin/sh -c /usr/bin/boinc --dir /home/aubin/boinc_data >/home/aubin/boinc_data/boinc.log 2>/home/aubin/boinc_data/boincerr.log (code=exited, status=2)
  Process: 29038 ExecStartPre=/bin/chown boinc:boinc /home/aubin/boinc_data/boinc.log /home/aubin/boinc_data/boincerr.log (code=exited, status=0/SUCCESS)
  Process: 29036 ExecStartPre=/usr/bin/touch /home/aubin/boinc_data/boinc.log /home/aubin/boinc_data/boincerr.log (code=exited, status=0/SUCCESS)
 Main PID: 29042 (code=exited, status=2)

nov. 30 21:16:15 breizh-atao systemd[1]: Starting Berkeley Open Infrastructure Network Computing Client...
nov. 30 21:16:15 breizh-atao systemd[1]: Started Berkeley Open Infrastructure Network Computing Client.
nov. 30 21:16:15 breizh-atao systemd[1]: boinc-client.service: Main process exited, code=exited, status=2/INVALIDARGUMENT
nov. 30 21:16:15 breizh-atao systemd[1]: boinc-client.service: Unit entered failed state.
nov. 30 21:16:15 breizh-atao systemd[1]: boinc-client.service: Failed with result 'exit-code'.

ls -ld /home/aubin/boinc_data
drwxrwxr-x 5 boinc boinc 4096 nov.  30 21:14 /home/aubin/boinc_data

Is there anything in boinc.log or boincerr.log?

What distro?