When you try to run files downloaded from the internet, the following error may appear on your Windows 10 computer:
In some systems, the same error may pop up also when opening Command Prompt or PowerShell.
This weird behavior by Windows 10 remains unexplained by Microsoft, but disabling Secure Boot in the BIOS helped many users. Note that this weird behavior may have nothing to do with the latest Feature Update for Windows 10, the Fall Creators Update.
How to disable Secure Boot in UEFI/BIOS Setup
Secure Boot is a feature of many newer EFI or UEFI machines which helps a computer resist attacks and infection from malware, and prevents it from booting into anything but Windows 8/10. When your computer was manufactured, UEFI created a list of keys that identify trusted hardware, firmware, and operating system loader code. It also created a list of keys to identify known malware. When Secure Boot is enabled, the computer blocks potential threats before they can attack or infect the computer.
To disable secure boot, use these steps:
- Turn off the computer.
- Turn on the computer, then immediately press ESC repeatedly, about once every second, until the Startup Menu opens.
- Press F10 to open BIOS Setup for HP and Compaq PCs. The key varies for other brands. It may be DEL, F2 or the F8 key in other systems. The POST screen will tell you which key should be pressed to get into the BIOS setup page. Or you can check the motherboard manual to get that info.
- Check the Boot Options or similar setting in the BIOS, and disable the option named Secure Boot. Here is a screenshot that shows how the Boot Options page might look like.
- For HP and Compaq systems, check out this page that explains how to enable or disable secure boot.
- Neosmart has an excellent guide with exact instructions and screenshots showing BIOS of ASUS, ASRock, HP, and Acer computers or motherboards.
Hope this temporary workaround helps prevent the annoying “Your organization used Windows Defender Application Control to block this app” error on your Windows 8 or Windows 10 computer.
About the author
Ramesh Srinivasan founded Winhelponline.com back in 2005. He is passionate about Microsoft technologies and has a vast experience in the ITeS industry — delivering support for Microsoft's consumer products. He has been a Microsoft MVP [2003 to 2012] who contributes to various Windows support forums.