operating system loader signature not found in SecureBoot database ('db'). All bootable devices failed Secure Boot verification

Is this a new system and it started right out of the box?  If not, ejn63 probably is correct about some change happening.  

Are you using the system with a dock?

Oops forgot link.

www.reddit.com/.../

Did you make any other changes than enabling secure boot (such as turning UEFI on or off)?

My laptop just started doing this today also. I just bought it a month ago. The battery died and afterward it came up running diagnostics and then with this error. The secure boot was not on, I turned it on trying to get it to work, then turned it off and now it is just sitting at the Dell emblem. The warranty person said that since the diagnostics ran and it said no hardware issues that they wouldn't fix it under warranty.

Sorry if this answer posts again, I don't see my reply.

No, I never made any changes, but an update was due to run and may have run.

I found this Reddit post that looks like it may correct the issue-so maybe it's a known issue? (Makes me a little angry that they may know about it, and have not deployed a fix, but will happily charge $211 to fix it).

I still don't know how I'm going to download the files and put on my laptop since it is my home PC. I am hoping to find another solution.

No, although it may have done an update and that may be the issue. I found this Reddit post with a fix, maybe a known issue?

www.reddit.com/.../

I still don't know how I'm going to fix since it's my home PC and it looks like you have to download files and load from an external drive.

Is the moderator just not posting my replies?

No, but an update was pending and could've ran. An article I read said that it is possibly a known issue with updates.

Thank you for your reply.

Ive disabled the secure boot and when i reboot my laptop, the DELL logo will appear as usual but it's stuck.

^^^ Same here.

Hi Mansoor,

thank you very much for your thread.

In my case your explanation worked, but when I shut down and start again the boot sequence has been deleted and I have to make the same procedure as you explained every time when I start my laptop.

Do you know if there is a way to save the boot sequence? Although I apply the new boot sequence (as you explained), there is not saved ;-(.

I have tried:

1- to have only one option in the list (Windows boot manager). In this case I receive a warning: "no bootable device"

2- to save the settings as user -> no improvement

It is very extrange because the new Name is not deleted "Windows boot manager" but the /EFI/BOOT/BOOTX64.EFI is changed to the old one and I don´t know why

Thanks in advance

When you are in Windows, could you open an admin command and type the following.  Copy and paste whatever shows up.

bcdedit

The normal boot path is:

\EFI\MICROSOFT\BOOT\BOOTMGFW.EFI

Mansoor's solution resolved the issue.

However, similar to lui, I have to repeat the steps everytime i reboot my laptop.

Any solutions appreciated

thank you. It is properly working.