Question Windows won't boot from HDD after disk swap

[MrTeal]

I have a Dell 790 SFF that had an existing installation on Windows hooked up to a scientific instrument. I've been working on some changes to the software and driver stack that talks to the instrument and didn't want to trial them on the existing install, so I popped out the hard drive for a new one and loaded a fresh copy of Windows to use. No problems there at all, but when I removed the new drive and put the old one back in it wouldn't boot from it and says no bootable media found. Running command prompt from the Windows Install Tool I can change to the C: drive and confirm Windows is still there, it just doesn't want to boot.

Any ideas?

 

[Z15CAM]

Appears you lost the "primary active" boot member on that disk - You can run the Windows Installation and select repair to rebuild the boot sector.

 

[MrTeal]

So I did get this working again. I had tried the repair off a Windows install stick, but it didn't work.
I ended up trying bootrec through the command line, but got an access denied error with /fixboot that I couldn't work around. I ended up having to delete and rebuild the boot partition and use bcdboot to rebuild the UEFI boot partition. Kind of a PITA, really.

 

[Z15CAM]

Good for you Mr Teal - In General WinX is a PITA ;o)