If you see this error appear on Mac, try these troubleshooting steps:
- Quit Day One, if open.
- Go to this folder in Finder: ~/Library/Group Containers/5U8NS4GX82.dayoneapp2
- Drag the folder the desktop.
- Re-open Day One.
- Go to Day One > Preferences > Sync and sign in to your Day One Sync account.
Contact the support team if you have any questions or concerns. http://dayoneapp.com/contact/