FixSoftware Installation

"Windows protected your PC": what the SmartScreen warning means

Learn why Windows shows the SmartScreen "Windows protected your PC" box, how to decide if the file is safe to run, and what to do next.

  • Updated
  • 7 min
  • Beginner
Applies to
  • Windows 11
  • Windows 10

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When you open a downloaded program, Windows may show a blue box that says "Windows protected your PC". Learn what that box means and how to decide whether to run the file, so you can act calmly instead of guessing.

Windows 10 no longer receives security updates

Support for Windows 10 ended on October 14, 2025. SmartScreen still works there, but an unsupported system is a poorer place to run software you are unsure about. See what to do about Windows 10 end of support.

What the warning means

The warning comes from Microsoft Defender SmartScreen. It checks the reputation of a file you downloaded before letting it run. According to Microsoft, it looks at two things:

  • The publisher. Is the file signed, and is the signing certificate from a known, trusted publisher?
  • The file itself. Have many people downloaded this exact file without signs of harm?

An unknown or negative result on either can trigger the box. That does not prove the file is harmful. Microsoft says even a signed program can show the warning until it has built up enough history, and an unsigned file starts with no reputation at all. New versions of unsigned programs can show it again.

What SmartScreen does with a download4 numbered steps, one under the other. The full text follows the picture.What SmartScreen does with adownload1You downloadA file arrives from a website ormessage2Windows checksPublisher and file reputationare looked up3Known and cleanThe program starts with nowarning4Not recognizedYou see Windows protectedyour PC
The warning means 'not recognized', not 'confirmed dangerous'.
Text version of this diagram
  1. You download: A file arrives from a website or message
  2. Windows checks: Publisher and file reputation are looked up
  3. Known and clean: The program starts with no warning
  4. Not recognized: You see Windows protected your PC

Decide whether to run the file

Ask where the file came from. This matters more than the warning itself. Microsoft advises downloading programs only from trusted publishers and retail websites.

Should you run this file?A top-to-bottom flow chart with 6 boxes. Work through them in order and stop when the problem is fixed. The full text follows the picture.Should you run this file?NoNoNo1Note where you got thefile2Did you choose it yourself,from the maker's own site?Yes: Go on to the next check3Does the publisher namematch the maker?Yes: Go on to the next check4Scan the file withWindows Security5Does the scan find nothing?Yes: You may choose RunanywayUnsure? Select Don't runand look for anothersource.
Any 'no' means stop. Closing the box is always safe.
Text version of this diagram
  1. Step 1: Note where you got the file
  2. Question 2: Did you choose it yourself, from the maker's own site? If yes: Go on to the next check. If no, go on to the next item.
  3. Question 3: Does the publisher name match the maker? If yes: Go on to the next check. If no, go on to the next item.
  4. Step 4: Scan the file with Windows Security
  5. Question 5: Does the scan find nothing? If yes: You may choose Run anyway. If no, go on to the next item.
  6. If nothing worked: Unsure? Select Don't run and look for another source.

Stop if someone told you to run it

Do not continue if a caller, a pop-up, an email or a chat message told you to download and run this file, especially to "fix" your PC or to let someone help you. That is a common scam route. Select Don't run, delete the file, and read how to spot tech support scams.

Check the file before you decide

Confirm the source

  1. Think back to where you downloaded the file. Was it the maker's own website, typed or found from a link you trust?
  2. If you are not sure, delete the file and download it again from the maker's official page. For programs from the Microsoft Store, see how to install software with winget and the Microsoft Store.

Scan the file

  1. Open your Downloads folder in File Explorer.
  2. Right-click the file and select Scan with Microsoft Defender. The name of this option can vary slightly between versions of Windows. If you do not see it, follow how to run a malware scan.
  3. Wait for the result. If a threat is found, delete the file and do not run it.

If you trust the file: run it once

  1. In the blue box, select More info. This reveals what Windows knows about the file. It may show the program's name and publisher, or say the publisher is unknown.
  2. Compare the name and publisher with what you expect.
  3. If everything matches and you trust the source, select Run anyway. This lets that one file start.
  4. If anything looks wrong, select Don't run and delete the file.

Windows may then show a User Account Control prompt. That is a separate permission step. Check the program name and select Yes only if it matches.

If there is no Run anyway button

Two common reasons:

  • Your administrator blocked it. Microsoft notes that enterprise policy can stop you continuing at all. This is usual on work and school PCs. Ask whoever manages the PC.
  • Smart App Control is on. Microsoft says it can be used on new Windows 11 installs only, and it is not available in Windows 10. Microsoft also says it blocks unsigned files unless they have a positive reputation.

Smart App Control settings

You can see its state under Windows Security then App & browser control then Smart App Control settings. Its modes are Evaluation (nothing is blocked while Windows decides whether your PC is a good candidate), On and Off.

Leave it on unless you are sure

Smart App Control is a security layer. Microsoft's page says that once you turn it on or off yourself, you cannot return to evaluation mode unless you reinstall or reset Windows. Look for a newer, signed version of the program from the maker, or a Microsoft Store version, before you change this setting. If you are unsure, leave it on and ask the program's maker.

Leave SmartScreen turned on

The setting is called Check apps and files, and it is under Windows Security then App & browser control then Reputation-based protection. Do not turn it off to get rid of one warning. Running the one file via Run anyway is the less risky choice.

Frequently asked questions

Does the warning mean I have a virus?

No. It means Windows does not recognize the file or its publisher. Your PC has not been checked and found infected. The file might still be harmful, which is why you check the source first.

Why do I see it on a program from a real company?

New programs and new versions can show it until they build reputation. Microsoft says this can take time. Confirm the download came from the company's own site.

Do apps from the Microsoft Store show this warning?

Microsoft says Store apps are never subject to SmartScreen download warnings, because Microsoft signs them.

The file keeps being blocked. What now?

Look for the maker's support page, or a Store version of the app. For install failures, see app won't install or run.

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Official resources used

Pages consulted while preparing this guide. Check them for the latest details.

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