Why Windows warns you

What you'll see

The first time you open the KopiaLens installer or the portable app, Windows may show a blue window titled Windows protected your PC.

Why it happens

Windows checks every downloaded program against two things: whether it is signed with a code-signing certificate, and whether many people have already run that exact file. KopiaLens installers aren't signed with a paid certificate, and each new version starts without a track record, so Windows treats it as unrecognised.

The notice is about the file being new to Windows. It isn't the result of a scan, and it doesn't mean anything was found.

Continue anyway

1. Choose More info.
2. Choose Run anyway.

Do this only for a file you downloaded from kopialens.com or the official KopiaLens releases page.

If there is no Run anyway button

Windows 11 has a stricter feature called Smart App Control. When it is on, it blocks unsigned apps and gives you no way to allow a single one. You can turn it off under Windows Security → App & browser control → Smart App Control settings. It protects the whole computer, so whether to turn it off is your call. On a work computer, an administrator's policy can also remove the button.

Check your download

Every release lists a SHA-256 checksum for each file in SHA256SUMS.txt. To compare yours, open Command Prompt and run:

certutil -hashfile "C:\Users\you\Downloads\KopiaLens-setup.exe" SHA256

Use your file's real path. The long string it prints must match the one listed for that file name. If you prefer PowerShell, Get-FileHash does the same.

Questions

Not sure about a download? Email support@kopialens.com or ask on Discord before you run it.