SimpleumSafe shows “Temporary storage could not be opened” when it cannot mount storage needed for temporary files. The explanation refers to error 12 and makes clear that your Safe password is not affected. macOS may also report that it could not open the disk image because of an incorrect password. That password reference concerns the temporary image. Error 12 alone does not tell us why the mount failed.
Check this first
- Quit SimpleumSafe and restart your Mac.
- Open SimpleumSafe again. Approve a Keychain access request if macOS shows one.
- Check whether the error appears again.
If the error returns
Even if this is the first time you open SimpleumSafe on this Mac, iCloud Keychain may still contain an item from an earlier installation on this Mac or another one. Such an item can prevent the temporary storage from opening. On one affected Mac, the message stopped appearing after the matching iCloud items were removed.
- Quit SimpleumSafe and open Keychain Access.
- Search for the full image identifier
D2E15CA8-8B51-4FF8-8A5C-A1AEDDFCCD21. Do not search only forworksparse. - Delete the results for this identifier that are marked “iCloud” in Keychain Access. There may be more than one. Leave results without the “iCloud” label unchanged.
- Open SimpleumSafe again and approve a Keychain access request if macOS shows one.
If the message still appears or there is no matching iCloud result, error 12 may have another cause.