Windows 10: Windows 10 re-writes BCD Timeout parameter when logging in on Dual Boot system

I am running a dual boot system Windows 10 / Windows 11 Insider Preview beta channel.I am able to successfully setting the Boot Configuration Data BCD Timeout parameter to 30 seconds to allow OS choice during bootup.I can do this using:1 Advanced system settings / Startup and Recovery2 msconfig3 Cmd; Bcdedit4 EasyBCDNo matter what I do, and ONLY when boot into Windows 10,as soon as I log in, Windows 10 OS overwrites the BCD store to skip Boot System Selection, setting the Timeout parameter to 1 second.This is super annoying and smacks of 'Microsoft knows best' actions taken by the OS w

:)

 

How to fix BCD for Dual Boot System

My bootloader is corrupted (I think the last Insider upgrade did it). I have the correct two Win 10 installations listed (my Win 10 production system and the Win 10 Insider) but there are others listed, such as "UEFI IP4" and both of my DVD drives (see screenshot). I would like to clear out the invalids but don't know how. I have EasyBCD and tried to recreate the bootloader but it corrupted it (and I recovered with Macrium Reflect).

Here is the screenshot:

 

How to clean up BCD entries? Rebuild the BCD?

This is normal that under Recovery Environment, The letters are re-assigned. This is why you have to be careful and select the correct one.
@dictum
Advice: Never use Easy BCD with Windows installed using GPT disk. Use Easy UEFI instead provided you know what you are doing. Easy BCD only works with MBR disk type.
Base on the screen shot above. Your disk 0 is your new Windows and your disk 1 contains the old Windows. Disk 3 contains a 512MB Fat32 partition and I don't know what that is. I suggest you disconnect disk 3 for now before proceeding.

Let rebuild new BCD's for both disk 0, and disk 1. Please follow step by step on the 2 screen shots below. On step 3, write down the drive letter for PM981_New. In the screen shot, My Windows is still assigned to C but it might be different from yours. In step 10, if the drive letter is different than C, then use the letter in step 3.

Do exactly the same for disk 1, this time select disk 1 in step 4 and assign letter V in step 7, Use V and the drive letter for Old Windows in step 10. This will create a new BCD for PM981_Old and you will be able to boot separately from boot menu.

From boot menu, select which one to boot from.
Once booted into Windows. If you wish, you can set up dual boot for Windows old & New. Under This PC, look for the drive letter of the offline Windows and type:
bcdboot X:\Windows where X is the letter of the offline Windows

 

Windows Update 1809 dual boot now corrupt

Hi,

Thank you for writing to Microsoft Community Forums.

I understand that you are unable to do a dual boot after an update. To narrow down the cause we will require a few more information from you. Please reply to the following details:

• Which operating system was installed first?
  
• Do you see any error message when you try to boot to Linux?
  
• Are you able to see the Linux OS files in the partition?
  

You can check for the boot timeout option whether the time to boot to the default OS is changed to 0 seconds. To check that, please follow the steps mentioned below:

1. Press and hold Windows + R key on the keyboard.
   
2. Type msconfig and click on OK.
   
3. Click on Boot tab.
   
4. Under timeout if you see time as 0 seconds then, change the time to at least 10 seconds.
   
5. Alternatively, you can check if Linux is listed or not.
   

Also, I suggest you to post a screenshot of Disk management with all the partitions.

Note: Make sure you don’t capture any personal information while taking screenshot.

Hope it helps.

Please reply with the status of the issue, we will be glad to help you further.

Nikhar Khare

Microsoft Community - Moderator