This article will tell you how to fix efi usb device has been blocked by the current security policy.

1.Solution

Use the following steps to change the Secure Boot setting:

  1. Completely shut down the computer.
  2. Power on the system. As soon as the first logo screen appears, immediately press F2 or Fn+F2 to enter the BIOS.
  3. Use the right arrow key to select Security.
  4. Press the down arrow key to select Secure Boot and press Enter.
  5. With the arrow key, highlight Disabled and press Enter.
  6. Press the F10 key and select Yes to save the changes and exit the BIOS

2.Reference

how to fix window boot manager has been blocked by the current security policy on acerv5window 8.1