Windows

Question

Win10 setup recognizes and doesn't recognize a partition

By dlewenstein ·
I'm still running Win8.1. I created a Win10 setup ISO file years ago during the period when Microsoft was offering the upgrade for free. I now burned it to a DVD, rebooted, and tried to install Win10.
Disk zero refers to a drive that has no relevance to this discussion.
Win8.1 is on my C; drive (Disk 1 Partition 1). When setup asked me where to install Win10, I specified Disk 2 Partition 2, which is 500GB. Disk 2 is a basic GPT drive. That's the part where setup recognized the partition.
I got an error message that setup was unable to create a new partition or locate an existing one. That's the part where setup didn't recognize the partition.
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All Answers

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I'll keep it short.

by rproffitt Moderator In reply to Win10 setup recognizes an ...

Windows no longer installs to a single partition. The setup will allow such to be selected but there are other partitions to be made so this story is not unique. Also, creating partitions before the W10 setup+install is too tedious and arcane so I'll stop here and share what I do next.

-> I delete that partition on that drive and then point the W10 setup to this unpartitioned drive.

Beware that it might only boot to W10 but recovering your old 8.1 is covered in other discussions so I'll stop here.

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I'm very happy to hear from you, Bob

by dlewenstein In reply to I'll keep it short.

(You knew me as doniel back on cnet's forums.) Thanks for the reply. I just want to make sure I understand you right. Delete partition 2 but leave partition 1?

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If that's the goal (try to keep W8.1)

by rproffitt Moderator In reply to I'm very happy to hear fr ...

Remember that there's a lot of priors about dual boots so I'm trying to keep it short that almost all Windows since about XP don't install to a single partition. Moving on.

So to have a dual boot you'll need not only your W8.1 install media handy, the W10 install media but be ready to research the web if the result ends up with a W10 only boot.

-> So yes to your question. We need a drive with unallocated space.

Read https://www.howtogeek.com/197647/how-to-dual-boot-windows-10-with-windows-7-or-8/ about this install. Notice the unallocated space.

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You may have misread

by dlewenstein In reply to If that's the goal (try t ...

While I certainly do want to keep my Win8.1 system, I asked about keeping partition 1 on disk TWO. Win8.1 is on disk ONE. I just wanted to make sure that you were saying I only need to delete the partition I want to install Win10 to.
I'll let you know how it goes when I'm done.

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Yes.

by proffitt In reply to You may have misread

You need unallocated space on the drive you want to install Windows to.

Mind you we only have English here and it would be inaccurate to write to delete the partition you want to install Win10 to.

-> Why I wrote "creating partitions before the W10 setup+install is too tedious and arcane" is because it is. I guess one could dive into what Win10's installer would need to install to a specific partition but again, no one to date has taken up that challenge. I did such long ago to see what it took and ended with "I'm not going to do that again."

So it's best to write we delete the partition on the drive we want Win10 to install on. Since that partition is now gone, it won't be possible to install to that now gone partition.

I hope you see how this works after you make your way through the gauntlet.

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Help!

by dlewenstein In reply to Yes.

The good news is that I was able to install Win10 by following your instructions. The bad news is that I can boot only into Win10. It took me a little while, but then I realized that my computer is no longer looking at my Win8.1 drive to check for a boot menu.
You mentioned that recovering Win8.1 is covered elsewhere. Can you point me to it?
Update: I suddenly remembered EasyBCD, downloaded it, and had to try several variations before I could get back into Win8.1. The only way I could do it was by making Win10 the default and then manually selecting Win8.1 from the boot menu. So I can still use a better solution.

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Try enabling the Windows Boot Manager.

by rproffitt Moderator In reply to Help!

Read https://www.reneelab.com/enable-or-disable-windows-boot-manager.html

I have had folk wipe out their other OS so this is not a sure thing. Dual OSes are very picky about installations so much so that I never will write how but reference the web articles I use to get such working.

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Solved with EasyBCD

by dlewenstein In reply to Try enabling the Windows ...

I wasn't happy with the methods provided, as they don't allow you to see what the BCD store currently looks like. It occurred to me that EasyBCD might work if run from Win8.1. EasyBCD shows the boot menu entries and just before them, it shows the default device. When I ran it from Win10 and tried to set Win8.1 as the default, it showed the EasyBCD default boot device as F: (and there's no way to change that). That's because when I installed Win10, the drive it was installed became C: and the drive on which Win8.1 was installed - my original C: - became F: (the letter that became available when I deleted the partition as you instructed). But that didn't work. Apparently, when rebooting, the Win8.1 drive was recognized as C: and the Win10 drive was seen as F:. However, when I ran EasyBCD from Win8.1, it showed the default (Win8.1) boot device as C:. I rebooted twice to test it, and when I manually selected Win10 from the boot menu, it booted into Win10, and when I allowed it to boot to the default, it booted into Win8.1. So. all's well.
Once again, thank you, Bob. As always, I'm grateful to you.

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Good sleuthing.

by rproffitt Moderator In reply to Solved with EasyBCD

I had EasyBCD in mind but wanted to try a solution native to Windows first.

Good job!

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Solved with EasyBCD

by dlewenstein In reply to Try enabling the Windows ...

I'm really frustrated. I wrote a long post and even edited it a couple of times, and when I reloaded the page, it was all gone.
I wasn't happy with the methods provided for enabling Windows Boot Manager, as they don't let you see what the BCD store currently looks like. You're working blind. It occurred to me that running EasyBCD from Win8.1 might do the trick. EasyBCD shows all the BCD entries and just before them, it shows the default. When I ran EasyBCD from Win10 and set Win8.1 as the default, EasyBCD showed "EasyBCD default device F:" (and the drive letter can't be changed). It showed F: because when I installed Win10, its drive became C: and my Win8.1 drive, which had been C: until then, became F: (the letter that became available when I deleted the partition as you'd instructed). However, it seems that upon rebooting, those drive letters became switched. When I ran EasyBCD from Win8.1 and set Win8.1 as the default, EasyBCD showed the default boot device as C:. I rebooted twice to test it, and when I manually selected Win10, it booted into Win10, and when I allowed it to boot to the default, it booted into Win8.1. So, all's well.
Once again, thank you, Bob. As always, I'm grateful to you.

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