Cannot install BootCamp because BootCamp’s partition not accepted by Windows installer

Question

Level 1

14 points

iMac Retina 5k 27” Late 2015 disk 2TB (Fusion drive)

macOS Big Sur version 11.5.2

Step by step to reproduce error:

copy window ISO file to desktop
start bootcamp assistant
slide bootcamp partition to give windows partition a size of 250GB (macOS will be 1.25TB)
bootcamp assistant download windows support software
bootcamp assistant starts windows setup automatically
windows setup: select language, time and keyboard
windows setup: press “Install Now”
windows setup: insert windows 10 product key and accept the license terms
windows setup: select “Custom install windows only”
windows setup: “Where do you want to install windows?” Drive 0 Partition 4: BootCamp is selected automatically, total size 234.7GB free space 234.6GB primary => press next
windows setup: continue process of installing windows (copy files, etc)
windows setup: installation is cancelled (see screenshot)

what can be the issue?

iMac 27″, macOS 11.5

Posted on Sep 12, 2021 10:10 AM

Reply

Answer 1

Level 9

59,536 points

Every EFI NO NAME indicates that an external storage devices was connected to the iMac, when Windows installer was initiated. This is invalid.

The following commands will remove convert these slices into Free Space. Be aware that disks can be renumbered when the Mac reboots. Verify that disk0 or disk1 is the correct disk. I will use diskN, where N can be 0 or 1, as you determine.
- diskutil eraseVolume free free diskNs10
- diskutil eraseVolume free free diskNs9
- diskutil eraseVolume free free diskNs8
- diskutil eraseVolume free free diskNs7
- diskutil eraseVolume free free diskNs6
- diskutil eraseVolume free free diskNs5
Run BC Assistant and let it clean up. It should remove OSXRESERVED and BOOTCAMP partitions
Disconnect all external devices, except Keyboard/Mouse/Trackpad
Run
- Reset SMC - How to reset the SMC of your Mac - Apple Support
- Reset NVRAM - Reset NVRAM or PRAM on your Mac - Apple Support
Run BC Assistant and try to install Windows.