operating system boot mode change (021)

[Vifki]

I needed dual boot with Linux and Windows 10 for my studies and now since i dont need linux i decided to remove it from my pc and decided to do full clean install on windows 10 by cleaning the both my SDD and HDD using DISKPART. After the installation i got blue screen error 0xc00000e which i fixed by switching the bios back to LEGACY mode. But now every second time i boot up the pc i get error (operating system boot mode change (021)  asking me to type a code and hit enter to change the bios settings or press escape to not do anything. And now the only button that i can press is ESCAPE i cant enter any numbers anywhere.

I STILL CAN USE THE LAPTOP by pressing ESCAPE the laptop shutsdown and than i can  boot it normally without a problem but the next time i turn it one start with the error(21) again.

[iomare]

Hi,

I would reinstall Windows in EFI mode (not legacy)

First, update the BIOS if available. Next download the latest Windows version and create a bootable pendrive. Set EFI in BIOS and boot from Pen Drive. Choose custom install and delete all partitions of the SSD, install in unallocated space. You could also at this point delete all the partitions from the HDD to be sure that it is not interfering.

https://www.microsoft.com/en-us/software-download/windows10

Hope it helps,

David

[Lil_Boy_Blue]

Hi

I don't know what error 21 is in your situation, but....

In Secure Boot there are "certificates/keys" embedded on the Main Board, and that may be your problem.

I have 3 "keys" one from HP, one Microsoft and the last from SuSE which I added myself.

So I suggest you have Secure Boot enabled and try from there, rather than Legacy and very little protection.