Windows Security or Smart App Control blocked an app? What to do

By Saadat Rafiq · 2 min read · 8 steps · Published 6 October 2026

Device

Windows

Shown on

Windows 11 Enterprise 25H2 (build 26200.9457), Microsoft Cloud PC

Real screenshots

6 of 8 steps

Checked

October 2026

Sources

3 official, linked below

Step by step

1. 

   Open Protection history

   Open Start, type Windows Security and open the app. Click Protection history on the left. Every threat Defender blocked or quarantined is listed with its date. Ours shows only two recommendations, no threats.

   Done

2. Restore a quarantined file you trust

   Click the item, open Actions and choose Restore. Defender then finds the file again and lists it as Threat found, action needed. Click that item and choose Allow on device. If you are not sure the file is safe, leave it in quarantine.

   Done

3. 

   Undo an allow later

   On the Virus & threat protection page, Allowed threats lists everything you allowed. Remove an item there and Defender blocks it again.

   Done

4. 

   Stop Defender scanning one folder

   If Defender keeps flagging a game or tool folder you trust, click Manage settings under Virus & threat protection settings and scroll to Exclusions, then click Add or remove exclusions.

   Done

5. 

   Add the exclusion

   Click Add an exclusion and choose File, Folder, File type or Process. A folder exclusion covers its subfolders too. Microsoft warns to do this only for files you are confident are safe. Ours has no exclusions.

   Done

6. 

   Check Smart App Control

   If no threat is listed in Protection history, Smart App Control may have blocked the app. Click App & browser control, then Smart App Control settings.

   Done

7. 

   Read its setting

   On blocks unsafe and unsigned apps. Evaluation, as on our Cloud PC, means Windows is still learning whether Smart App Control suits you and switches it on or off by itself. Off stops it. Microsoft says there is no way to allow one app; only switching it off helps.

   Done

8. Decide before you switch it off

   Switching it off is your choice for an app you trust. Microsoft says recent updates let you switch it back on without reinstalling Windows. The other route is to ask the app's maker to sign it.

   Done

About this guide

Two different parts of Windows Security block apps. Microsoft Defender Antivirus quarantines files it thinks are harmful, and those can be restored. Smart App Control blocks apps it cannot confirm as safe, often unsigned tools, mods and older games, and it cannot make an exception for one app. Find out which one it was before you change anything.

The screenshots are our own, taken on Windows 11 Enterprise 25H2 (build 26200.9457) running as a Microsoft Cloud PC, a Windows PC that runs in the cloud. The Settings app is the same on Home and Pro PCs; where the Cloud PC shows something different, the step says so.

Good to know

If Smart App Control is Off on your PC, it did not block the app. Look again at Protection history and at Reputation-based protection on the App & browser control page.

Run a scan after anything suspicious: how to scan a Windows 11 PC for viruses with Windows Security.

In short: Windows Security, Protection history: restore and Allow on device for a quarantined file you trust, or add an exclusion. Smart App Control has no per-app exception: App & browser control, Smart App Control settings, Off.