synology cannot login to the system because the disk space is full

On my Synology NAS box I got this error message when trying to login to the admin console (synology cannot login to the system because the disk space is full) and was not able to login.

I could still telnet to the box so issued a reboot command.

 

After the device had rebooted still could not login so after a bit of hunting issued these commands.

  • Login to SSH using root / [password of admin user]
  • cd /
  • rm .syno/patch/*

It looks like a failed upgrade.