Windows protected your PC 🪟 Windows

Windows protected your PC — Microsoft Defender SmartScreen prevented an unrecognized app from starting

SmartScreen blocked an app that’s unsigned or new/rare (no download reputation yet).

Seen on: Windows

Meaning

Users can click More info → Run anyway for trusted software. Developers avoid it by signing with a code-signing certificate (EV certificates gain reputation immediately) and building download reputation.

Common causes

  • Unsigned executable or installer
  • New certificate/app without reputation
  • Downloaded file marked with Mark-of-the-Web

⚡ Quick fix

  1. Verify the publisher/source, then More info → Run anyway
  2. Developers: sign binaries (signtool) with an OV/EV certificate
  3. Distribute via Microsoft Store or winget for trusted delivery

Detailed fix by platform

Windows

  1. powershell
    signtool sign /fd SHA256 /tr http://timestamp.digicert.com /td SHA256 /a MyApp.exe
Unblock-File .\MyApp.exe   # removes Mark-of-the-Web for a file you trust

How to diagnose

  1. Signature — File Properties → Digital Signatures
  2. Source — Trusted download?

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

🧠 Still stuck? Analyze your error

Paste the full message, response headers or stack trace — we'll detect the platform and point to the most likely cause.