BackupOnShutdown can back up open or locked files on Windows when you start the app as administrator. It then uses Volume Shadow Copy to read files another program is still using. Without administrator rights, files it can't read are skipped and reported at the end; other files can still be saved.
Why were open files skipped?
A program can hold a file so that nothing else is allowed to read it. BackupOnShutdown can only save what it can read, so an open spreadsheet, a mail store, or a database file may be left out while the rest of the backup still completes. Read the summary before you assume the whole run failed.
For an ordinary document, saving and then closing the program is often enough. A database, a mail program, or a background service can keep files in use after its window is gone, so don't stop a service you don't recognize just to clear a warning.
Folders you chose to skip are a different case. Administrator rights do not put them back. If a file seems to be missing, check Folders to skip on that backup as well as the summary. Excluding folders explains how that list works.
How do I include open files on Windows?
When files were skipped, the summary can say "To include files that are open, start BackupOnShutdown as administrator."
- Let the current backup finish, or choose Cancel and wait until it has stopped.
- Close BackupOnShutdown.
- Find the app in the Start menu, right-click it, and choose Run as administrator. Approve the Windows prompt if you're allowed to.
- Check that the backup drive is connected, then choose Back up so you can read the result without shutting the computer down.
Everyday backups of readable files don't need administrator rights. You can also find this guidance under Settings → Backup → Advanced, in Files that are open.
Save your work in other programs even when you use Volume Shadow Copy. Anything that has never been written to disk is not on the shadow copy, so administrator rights cannot include it.
What can Volume Shadow Copy still not promise?
Administrator rights don't guarantee that every file will be readable, or that a running application will leave a usable copy of its data. Permissions, a failing drive, and the way a program stores its files can still get in the way. For a live database or another specialist application, use that application's own backup or export as well.
After the retry, Backup finished and Backup finished, with a few problems mean different things. Read Details for any reported problems; during the backup, Show details displays the activity log. Bring an important file back with Restore files into a new empty folder, and open that copy in its usual program before you rely on it. Leave your current working file where it is while you check.
If the app can't count the files, it says "Some files could not be read and were skipped. They may have been open in another program." Check Details for any affected paths, compare them with your folder selection, and retry after addressing the reported problem.
A run that skips unreadable files is incomplete. If you had chosen Back up & shut down, the computer stays on so you can deal with the result, which does not mean nothing was saved. The failed or incomplete backup guide covers the other reasons a shutdown doesn't happen.
What about macOS?
These steps apply to Windows. macOS has no Volume Shadow Copy, and the Mac version has no administrator option: a file another app has open is read as it is when the backup reaches it. Files that macOS privacy protection blocks are skipped and listed after the backup. To include them, allow BackupOnShutdown under System Settings → Privacy & Security → Files and Folders. Photos and other protected app data need Full Disk Access there.
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