Reference

Troubleshooting

What the messages SilentBox shows mean, and what to do about each one.

You can't unlock

After a wrong password, the lock screen asks you to wait ("Try again in … seconds"), a little longer after each wrong try. Check the password and wait it out.
If you've forgotten the password, tap Forgot Password? and use your recovery phrase. See If you forget your password.
If your PIN isn't accepted, tap Use Password Instead. Unless Two-Step Unlock is on, SilentBox turns the PIN off after 10 wrong tries; your password still opens the vault.
This vault cannot be opened with a password here — part of the vault's key is missing from this device's iCloud Keychain. This can happen after signing out of your Apple Account without keeping the Keychain on this device. It isn't your password, and nothing in the vault was deleted. Signing back in brings it back; meanwhile, Face ID or Touch ID or your PIN open the vault if they're set up here. If none of that works, Forgot Password? removes the vault from this device.

Only in iCloud, with a count — some of the items you're exporting aren't downloaded to this device. Choose Download and Export to include them, or Export Downloaded Only.
Some items weren’t exported — those items aren't on this device and couldn't be downloaded from iCloud. Connect to the internet and export them again.
"Some albums are locked, so nothing was backed up." — start the backup again and confirm it's you when SilentBox asks.
When restoring, "The archive could not be unlocked." means the archive's password is wrong. Enter the password you chose for the archive, not your vault password.
Import Finished saying there was nothing new to restore isn't an error: everything in the archive was already in your vault.

This item isn’t on this device. — it's in iCloud. Connect to the internet and open it again.
Not in iCloud yet — the device it was added on hasn't uploaded it. Open SilentBox on that device and it arrives on its own.
This item is on another device. — its album isn't synced with iCloud. Turn on iCloud sync for the album to bring it here. See Choose albums for iCloud.

If the devices that had some items no longer have them, More in the album offers to move those items to the Trash.

The result of the last sync is under Sync Now in Settings, in the iCloud section.

"To sync, sign in to iCloud in Settings." — sign in to your Apple Account in the Settings app.
"Your iCloud storage is full." — free up iCloud storage or upgrade it. Your vault uses your own iCloud storage, not ours.
"Your iCloud account is temporarily unavailable." — sign out of iCloud and back in, in the Settings app.
"Can’t connect to iCloud." — SilentBox tries again later on its own.
"Another device set up syncing with a newer version of SilentBox." — update SilentBox on this device.
"iCloud has a different vault than this one." — nothing was synced, so neither vault was overwritten.
Sync paused because your trial ended — sync needs the Full Version. Nothing is removed from iCloud. See The Free Trial and the Full Version.

Item List Can't Be Read in Settings — this device can't read the vault's list of items, so sync is stopped to keep anything from being overwritten. Remove Unreadable Data from This Device removes only the unreadable data here and downloads the vault from iCloud again. Anything that exists only on this device is deleted for good.
"This vault’s list of items was restored from an older copy." — items you deleted since then may reappear, and recent changes to albums and names may be missing.

"There isn’t enough free memory right now." — close some other apps and try again.
Vault Deleted — the vault was deleted on another device, so it's no longer available here either.
After restoring your iPhoneiPad from a device backup, the vault isn't there: it's never part of device backups. It comes back through iCloud, or from an archive.