I've installed Windows 10 with Bootcamp on a new iMac with Mojave.

Now I can't boot to MacOS volume.

1) Bootcamp tool in Windows don't see volume as bootable.

2) Option click on restart don't show a menu to choose, only when bootable usb is connected

3) If I boot to installation USB, I can see this volume, but Startup can't choose this volume: The bless tool was unable to set the current boot disk...

I read some bootloader repair guide with changing partition size, but I don't know how to do that with hybrid drive.

Any suggestions?

  • Are you sure you haven't wiped the macOS volume when you installed Windows?
    – airsquared
    Oct 21, 2018 at 20:30
  • I'm sure. I can see it in 3)
    – Geo B
    Oct 21, 2018 at 21:09

1 Answer 1


Some strange thing happened.

I switched iMac off (like I did before for several times to restart) and let it be off for a time while I compiled fresh Mojave installation usb drive.

And after turning on iMac started to react on Option key, so I could choose MacOs volume to boot and it's booted successfully. Usb installation flash was plugged in.

Now this Option key boot menu is available without usb-flash plugged in...

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