Windows or Mac blocks the installation
Installing an app from a small publisher often triggers a warning. It does not mean the file is infected: the system simply does not know the publisher yet. Here is how to check the file, then open it.
1. Why the warning appears
Windows and macOS trust apps from publishers they already know: big companies that pay for a code-signing certificate and have millions of downloads behind them. A new app from an independent publisher has neither, so the system plays it safe and asks you to confirm.
Before going further, make sure the file comes from the official site. The SHA-256 fingerprint published next to each download lets you check that it has not been modified on the way.
2. Windows: "Windows protected your PC"
This blue window is SmartScreen. It appears the first time you open the installer.
- Click "More info" under the text.
- The publisher name and a "Run anyway" button appear. Click it.
- Windows may then ask for permission to make changes: answer Yes.
- The warning does not come back for this version.
3. Windows: the browser blocks the download
Edge or Chrome sometimes stops the download with "isn't commonly downloaded".
- In Edge, open the downloads list, click the three dots next to the file, then Keep, Show more, Keep anyway.
- In Chrome, click the arrow or three dots next to the download, then Keep or Download dangerous file.
4. Mac: "Apple could not verify"
Gatekeeper shows this message for apps that do not come from the App Store or from a developer registered with Apple.
- Drag the app into the Applications folder, then double-click it once and close the message with Done.
- Open System Settings, Privacy & Security, and scroll down to the Security section.
- Click "Open Anyway" next to the app name and confirm with your password.
- The app opens. Next time, it starts normally.
5. Mac: "is damaged and can't be opened"
On a Mac with an Apple chip, this message can appear for an app downloaded outside the App Store even though the file is intact. It is the download quarantine that blocks it.
- Open Terminal (Applications, Utilities).
- Type: xattr -dr com.apple.quarantine "/Applications/App name.app" replacing the name with the app's name, then press Enter.
- Open the app again.
6. Linux
Linux does not block apps in the same way, but an AppImage file must be made executable: right-click, Properties, Permissions, tick "Allow executing file as program", or in a terminal chmod +x on the file. A .deb package installs with a double-click or with sudo apt install ./file.deb.
The tool
All KDL TECH apps can be downloaded for Windows, macOS and Linux, with the SHA-256 fingerprint of each file next to the download link.