Hello to everyone.
At the beginning I'd installed windows 10 with the legacy BIOS-MBR boot mode,but since I needed a Windows 10 installation that was able to boot using the EFI partition style,I have converted the partition scheme from MBR to UEFI with a tool and after this operation I have reinstalled Windows 10 from an old backup. This backup comes from the old BIOS/MBR installation of Windows 10. When I tried to boot Windows,I realized that it was not able to do that (no error message.but blinking cursor). I have so realized that the EFI partition didn't exist. So,I have created a new FAT32 partition and I have repaired the EFI partition following this guide :
How to Restore Deleted EFI System Partition in Windows 10? | Windows OS Hub
it worked,but only partially. Infact,since I need to put the "TESTSIGNING ON",when I gave this command :
Bcdedit.exe -set TESTSIGNING ON
I've got this error :
The boot configuration data store could not be opened. The volume for a file has been externally altered so that the opened file is no longer valid.
I tried a lot of methods to fix it,but right now unsuccesfully. Can someone help me ? thanks.