Confirming iCloud Data Loss
As part of Apple's migration from iCloud to iCloud Drive, there tends to be a bit of a delay in seeing your entries reappear in Day One. (For more details about iCloud Drive see: iCloud Drive FAQ.)
To confirm whether or not your entries are still in iCloud, please follow these steps:
Go to Settings > iCloud > Storage > Manage Storage > Day One
To the far right of Documents & Data, you should see the amount of data (in MB) stored on your device. Depending upon your journal size and the amount of photographic entries you have, this should be 50 MB or higher, and is a pretty good indication that your data has not been permanently lost, but is just not appearing in Day One (yet).
Tap entries (or photos), then you should see the filenames of your entries (or photos) listed.
If it looks like your data is still available in iCloud, it is likely there is a delay in getting your data to reappear in Day One. You should see something at the top of the Main Menu in Day One that shows entries/photos/data are downloading. If you don't see this, or it appears to be frozen, toggle iCloud syncing off/on in Day One, reboot your device, then come back to Day One. You should see something that indicates entries are downloading. It will take some time, but they will come back eventually. Ideally, keep Day One open and active as the entries download.
Data Recovery Options
If data loss occurred, there are several options available for restoring your data. In descending order of preference, these options include:
Day One Mac Automatic Journal Backups
Mac OS X Time Machine Backups
iTunes File Sharing Backups
A. Day One Mac Automatic Journal Backups
Data available: Text and Photos
The Mac version of Day One automatically backs up your entire journal at specified intervals when your Mac is opened. If you don't open your Mac app periodically, your journal will not be backed up. The default setting for backups is every two days with a maximum of 20 backups stored at any time. These default settings can be changed in Day One Mac > Preferences > Backup.
For more information on restoring entries using this method, see: How do I restore from a backup?
B. Mac OS X Time Machine Backups
Data available: Text and Photos
If you have Time Machine backups and use the same iCloud account on all your devices, you may be able to find some of your entries using a Time Machine backup. Note that this applies even if you only have Day One on a mobile device, but your computer is a Mac; it's not necessary to have the Mac version of Day One.
Follow these steps:
Finding Journal Data in Time Machine
Open Finder, and paste this path into Go > Go to Folder: ~/Library/Mobile Documents/5U8NS4GX82~com~dayoneapp~dayone/Documents/Journal_dayone Tap the Go button.
Click the Time Machine icon in the menubar, then click 'Enter Time Machine.'
Choose a past date in Time Machine that you think should have a copy of your missing content.
Control-click the “entries” folder inside the “Journal_dayone” folder, then click "Get Info" to view details of this folder.
In the folder details window, find the number of items in the folder.
If the number of items matches the number of entries in your journal prior to data loss, copy the “entries” and “photos” folders to your current Mac Desktop.
If the number of items seems wrong, repeat steps 1-4 until you find a suitable backup.
Once you find the desired backup folder, please contact support for further assistance.
For more information about Time Machine, see: Mac Basics: Time Machine backs up your Mac
C. iTunes File Sharing Backups
Data available: Text
Day One makes a backup of the text portion of the user's journal entries just before Day One is updated; the first time Day One is opened after iOS is updated; and once a week (the app has to be open for a weekly backup to take place). The 20 most recent backups are retained.
These backups are stored within the Day One area in the filesystem of the mobile device, and are accessible via the File Sharing area in iTunes. Please note: any time you delete Day One, all previous backups are also deleted, as they are stored in the Day One area in the device filesystem.
To recover entries via a Mac or PC, follow these steps:
Open iTunes on your Mac or PC. On macOS 10.15 (Catalina), connecting the iOS device will use Finder instead. Details here: https://support.apple.com/en-us/HT201301
Connect your iOS device. (Dismiss any prompts or stop any processes to back up your device.)
Select the iOS device in the sidebar or top-bar (depending upon your version of iTunes), then go to the Apps tab.
Scroll down to the “File Sharing” section, then click Day One in the list of apps.
Click the Backups folder, then click the “Save to…” button and save the folder to your Desktop.
Zip this folder and send it to the Day One Support Team via this form—http://dayoneapp.com/contact)
Restoring Data using a Mac
After sending the ZIP file to support and receiving a file back, follow these steps to restore your data:
NOTE: A Mac and Day One 2.0+ is required for these steps.
Download the file given to you by support.
Drag the file onto Day One 2.0 and the files should import.