System won't boot after removing second hard drive, EFI?

A quick thank you for the great info. I'll see what I can do with it all when I get a chance this weekend. I just wanted to post and let you know I appreciate it.

Also, you are correct: without doing anything else, the start-up repair didn't do anything except give a compatibility error.

Did you Mark Win7 Partition Active first before running Startup Repair - Run up to 3 Separate Times?

You can run repair as many times as you want but it won't write the system boot files to C without being marked Active first, which points the repair utility to the intended boot partition.

But if this is a UEFI BIOS it will not work unless you follow the steps given by Saltgrass, or reinstall to UEFI (Unified Extensible Firmware Interface) - Install Windows 7 with - Windows 7 Forums. So check your BIOS to see if it is UEFI BIOS vs. Legacy BIOS - YouTube

I just moved my EFI partition from my secondary HDD to my primary HDD on my x64 Windows 8.1 installation, because I wanted to remove the secondary HDD. Using the steps Saltgrass provided I have been able to do this. At first I forgot to remove the secondary HDD which caused the bcdboot command not to execute the proper tasks. The second time I did remove the secondary HDD and now everything works perfectly.

Kaktussoft said:

With both disks attached Do this:

Bootmgr - Move to C:\ with EasyBCD

Then mark 100MB partition on old drive inactive to prevent to use it as BOOT partition
Partition - Mark as Inactive

Now it works

Thanks for the info on EasyBCD

Followed these instruction and but did not work at first. I added the Windows 7 to Boot menu list of OS's and that worked perfectly. I know this thread is old, but hope it helps out.

If you'd like we can look over a screenshot of your Disk Management - Post a Screen Capture Image to see if everything looks correct.

Saltgrass said:

This post concerns restoring boot capability to a UEFI install when the install drive being used does not have a EFI partition, such as the situation in this thread.

The overall process is much like a Legacy (MBR) install where you do not have an active partition with the boot files included. But basically, you have to create a 100 MB EFI partition, format it with FAT32, and install the boot files.

All boots have to be done to the UEFI version of the media, whether flash drive, Install DVD, or actual install. Using the F8 or F12 keys, or whatever your system used for a boot device menu, is usually best. Since the boot device can change, you need to choose it prior to every boot.

Start by configuring the partitions on the new primary drive while still in Windows 7 using Disk Management. You can do this in Diskpart, but easier here. The end result has to be at least 100 MB of unallocated space on the drive.

Now, shutdown and disconnect the old drive, and any external drives you don’t need. Reboot into the Install Media and go to the page where you would normally select to Install, but do not. Instead, use the Shift+F10 key combination to open a command prompt window.

Type the following commands with enter after. Comments are for information, and not to be entered. You can use the first 3 letters of most words, except for Diskpart.

Diskpart
List Disk
<- check for the drive you will be using and note the number.
Select disk 0
<- use the number for you drive, if using flash drive, be careful and don’t select it.

Create partition efi size=100
<- size= designation only used if more than 100 MB available. If you left exactly the correct room on the drive, remove the size=100.

List Partition
<- just to verify the correct partition is selected by checking for asterik on left.

Format fs=fat32
<- after creating a partition, it normally becomes the selected partition. If you want to make sure, use the List Partition command and then select the partition you need with select partition 3 for example. An asterisk on the left side will designate what is selected.
Note: If a command you use shows Volume numbes instead of Partition numbers, Volume numbers and Partition numbers may not always agree, so use what is shown. If you select the wrong partition, you may wipe out your install.

Exit

We have left Diskpart, and back in the Command Prompt window. Now we need to put the boot files in the new partition. In the command prompt window, switch to the OS install partition, normally C: and it would be good to do a dir command and make sure the Windows folder is listed.


C:
Dir
<-check for Windows folder. If another drive letter shows as the OS install use it in the next command.

Bcdboot C:\Windows

Wait for it to finish and give the successfully created message. You can now exit the install and should now be able to select the Windows Boot Manager during restart and boot into your Windows 7 install. If still not able to boot, do a Repair Install. See the attachment for actual command window.

Saltgrass's instructions worked to fix my Windows 8.1 issue where the boot files were accidentally installed on a the 2nd HDD. Initially I did a fresh install of Windows 8.1 on a new SSD when I still had my old HDD installed in the PC (mistake). Windows 8.1 installed and worked fine, but I could not delete a small partition on the 2nd HDD (even using DiskPart) and then I realized that the system would not boot unless the 2nd HDD was installed. The reason was that the boot files were residing on the HDD. If I ran "Bcdboot C:\Window /s C:" in admin cmd (or repair cmd) it would tell me say that the boot files were created, but they were not - the reason is because I needed to create a separate 100MB partition on my new SSD. Creating the EFI partition (as per Saltgrass's instructions) fixed this! Now my machine boots properly. THANKS!

Saltgrass said:

This post concerns restoring boot capability to a UEFI install when the install drive being used does not have a EFI partition, such as the situation in this thread.

The overall process is much like a Legacy (MBR) install where you do not have an active partition with the boot files included. But basically, you have to create a 100 MB EFI partition, format it with FAT32, and install the boot files.

All boots have to be done to the UEFI version of the media, whether flash drive, Install DVD, or actual install. Using the F8 or F12 keys, or whatever your system used for a boot device menu, is usually best. Since the boot device can change, you need to choose it prior to every boot.

Start by configuring the partitions on the new primary drive while still in Windows 7 using Disk Management. You can do this in Diskpart, but easier here. The end result has to be at least 100 MB of unallocated space on the drive.

Now, shutdown and disconnect the old drive, and any external drives you don’t need. Reboot into the Install Media and go to the page where you would normally select to Install, but do not. Instead, use the Shift+F10 key combination to open a command prompt window.

Type the following commands with enter after. Comments are for information, and not to be entered. You can use the first 3 letters of most words, except for Diskpart.

Diskpart
List Disk
<- check for the drive you will be using and note the number.
Select disk 0
<- use the number for you drive, if using flash drive, be careful and don’t select it.

Create partition efi size=100
<- size= designation only used if more than 100 MB available. If you left exactly the correct room on the drive, remove the size=100.

List Partition
<- just to verify the correct partition is selected by checking for asterik on left.

Format fs=fat32
<- after creating a partition, it normally becomes the selected partition. If you want to make sure, use the List Partition command and then select the partition you need with select partition 3 for example. An asterisk on the left side will designate what is selected.
Note: If a command you use shows Volume numbes instead of Partition numbers, Volume numbers and Partition numbers may not always agree, so use what is shown. If you select the wrong partition, you may wipe out your install.

Exit

We have left Diskpart, and back in the Command Prompt window. Now we need to put the boot files in the new partition. In the command prompt window, switch to the OS install partition, normally C: and it would be good to do a dir command and make sure the Windows folder is listed.


C:
Dir
<-check for Windows folder. If another drive letter shows as the OS install use it in the next command.

Bcdboot C:\Windows

Wait for it to finish and give the successfully created message. You can now exit the install and should now be able to select the Windows Boot Manager during restart and boot into your Windows 7 install. If still not able to boot, do a Repair Install. See the attachment for actual command window.

Amazing post; just exactly the solution I required (RE creating and formatting EFI partition then adding files).

Is there any possibility of using this method, but without having to take out the second HDD? I've installed Windows 10 on an SSD, with my old HDD in a optical drive HDD caddy. But to remove it, requires opening up my laptop, whose screws are failing and I would like to avoid doing so...