Windows 11 refuses to open a program you have just downloaded, and the block comes from Smart App Control? This guide explains how this protection decides to block an app, how to check that it is really the cause, and which options actually exist, based on Microsoft's support pages. One key point to know from the start: Microsoft states that there is no way to allow a single app blocked by this protection.
Problem
- A downloaded program or installer refuses to launch and Windows says it was blocked for your protection.
- The block happens every time, even after downloading the same file again.
- You cannot find any button to run it anyway or to add it as an exception.
- The PC runs Windows 11 and Smart App Control is turned on.
Observe before acting
Several Windows protections can block a program. First identify which one is involved:
| Observation | Most likely cause | Step |
|---|---|---|
| Blue "Windows protected your PC" screen with a More info link | SmartScreen filter, not Smart App Control | See the guide on the SmartScreen warning (French guide) |
| Microsoft Defender notification about a quarantined threat | Antivirus | See File wrongly blocked by Microsoft Defender: what to do (French guide) |
| Message saying only Microsoft Store apps are allowed | Windows 11 in S mode | See Unable to install an app in S mode on Windows 11 (French guide) |
| The block mentions Smart App Control, or Smart App Control is set to On | Smart App Control | Steps 1 to 4 |
How Smart App Control decides
According to Microsoft's FAQ, when you launch an app, Windows first queries a cloud service that predicts whether it is safe. If the service cannot make a confident prediction, Windows checks the program's digital signature: an app signed with a trusted certificate is allowed, an app that is unsigned or has an invalid signature is considered untrusted and blocked. This is why legitimate but little-known software, or software distributed unsigned by small developers, can be blocked.
The protection has three states, shown in Windows Security:
| State | Effect |
|---|---|
| Evaluation | Windows observes your usage to decide whether it can turn it on without getting in your way. Nothing is blocked. |
| On | Apps judged malicious or untrusted are blocked. |
| Off | This protection no longer blocks anything. |
Microsoft states that the protection works in addition to Microsoft Defender or your antivirus, and that it does not exist on Windows 10.
Step 1: check that Smart App Control is really what is blocking
When to use it: always first, so you do not turn off a protection that is not involved.
Suggested solution
- Open Windows Security (type "Windows Security" in the taskbar search box).
- Go to App & browser control, then open the Smart App Control settings.
- Read the state shown: Evaluation, On or Off.
Expected result: if the state is Off or Evaluation, the block comes from another protection: go back to the "Observe before acting" table. If it is On, go to step 2.
Step 2: check where the file comes from and look for a signed version
When to use it: Smart App Control is on and blocks a specific program.
A block is not an error to bypass by reflex: the protection judged the file untrusted, which can also point to a modified or malicious file.
Suggested solution
- Check where the file comes from: download it only from the publisher's official website, typing its address yourself rather than following a link received in a message.
- If a version is available in the Microsoft Store, prefer it.
- If the program really comes from the official publisher, contact them: Microsoft recommends asking them to sign their app with a valid certificate. A signed version can then be allowed.
- If you have the slightest doubt about the file, do not run it and have it scanned by Microsoft Defender or your antivirus.
Expected result: an official, signed version of the program installs without being blocked, without touching the protection.
Step 3: turn off the protection, knowingly
When to use it: only for an app you are sure about (known publisher, official website, no detection by your antivirus), which is still blocked and for which no signed version exists.
Microsoft is clear: there is currently no per-app exception. The only way to use a blocked program is to turn off Smart App Control entirely. Microsoft Defender or your antivirus keeps working, but this extra layer of protection no longer applies to any app.
Suggested solution
- Open Windows Security > App & browser control > Smart App Control settings.
- Select Off and confirm.
- Launch the app, then check in step 4 whether you can turn the protection back on.
Expected result: the app launches.
Be careful about turning it back on. For a long time, once the protection was turned off, you had to reinstall or reset Windows to turn it back on. Update KB5079391 of March 26, 2026 (Windows 11 versions 24H2 and 25H2) announces that it becomes possible to turn it on or off without a clean install, with a gradual rollout. So check in the settings page whether the On option is still offered after turning it off before you make your decision. If it is not on your PC, consider turning it off as lasting.
Step 4: turn the protection back on when possible
When to use it: the protection is off, or stuck in the off position, and you want it back.
Suggested solution
- Install the latest updates: Settings > Windows Update > Check for updates. Also update Windows Security, Microsoft Defender and your other Microsoft Store apps, as Microsoft advises.
- Go back to the Smart App Control settings and choose On if the option is available.
- If the option stays greyed out, see the table below.
Expected result: the state shown is On again.
Special cases
| Situation | Explanation given by Microsoft |
|---|---|
| PC managed by a company or school | The protection is turned off on managed devices: contact your IT department. |
| Developer mode turned on | The protection is turned off in this case. |
| PC in S mode | You need to switch out of S mode, then reset the PC to be able to turn the protection on. |
| Optional diagnostic data turned off | Microsoft says you need to reset or reinstall Windows and choose to send optional diagnostic data. |
| PC still in Evaluation mode | Evaluation mode blocks nothing. Once it has ended, you cannot return to it without resetting or reinstalling. |
| A legitimate app is blocked and you think it is unjustified | Report it through the Feedback Hub (Windows + F keys), category Security and Privacy, then Smart App Control. |
Final check
- ☐ You confirmed in Windows Security that Smart App Control is causing the block.
- ☐ The file comes from the publisher's official website, or from the Microsoft Store.
- ☐ You looked for a signed version or contacted the publisher before turning off the protection.
- ☐ If you turned it off, you know whether your PC lets you turn it back on.
- ☐ Windows and Microsoft Defender are up to date.
Sources
- Microsoft: Smart App Control frequently asked questions
- Microsoft: App & browser control in the Windows Security app
- Microsoft: March 26, 2026 — KB5079391 (OS Builds 26200.8116 and 26100.8116) Preview (Smart App Control section)
Still having the problem?
Reply in this topic with your Windows 11 version (Windows + R keys, then winver), the state shown in the Smart App Control settings, the name of the blocked app and the website you downloaded it from, and the exact text of the block message. Never post a password, a licence key or personal information.