bootcamp mojave mess

[WayneColo]

I tried to put bootcamp on my old mac mini which had mojave installed.
it appears that the mojave portion of this disk has disappeared.
it was a 500 Gig drive, and I told it to make a 100G partition for the win10 install
which is the case now.
But now, I don't see any way to boot into mojave.
holding the option key down doesn't bring up the boot menu.
and in windows I can't see any partition for the mojave portion,
tho' I don't know if I should. Windows probably can't see the Mac piece.
I put the usb stick in to see if I could reinstall mojave, but windows wants to format that.

at a loss, right now.
I think this is the reason I've run macs for 15 years and never tried
to put a bootcamp windows version on.

 

[WayneColo]

I have found some other threads with this topic.
Maybe I can find my answer there.

 

[DeltaMac]

A standard installation of Windows 10 cannot see your Mojave drive, which would be formatted APFS. Windows 10 won't see it at all.
You said you "put the USB stick in"
Is that USB stick a bootable Mojave installer?
If yes, shut your mini OFF.
insert the Mojave installer.
Boot while holding the Option key. Choose the installer from that boot picker screen, and press Return to boot to that.
Open Disk Utility. What appears in the list on the left side of that Disk Utility window?
Be sure to click the View icon, and change that to "Show All Devices"
You should see your drive, with all partitions. The Mojave volume will have a Container with your Mojave boot drive inside that container.
And, you should also see your BOOTCAMP drive.

I suspect that you wiped out your Mojave volume. The Windows install gives you the opportunity to do exactly that, when you see the list of available partitions that you can use. You have to be very careful at that point. But, choosing to make a 100GB partition in the bootcamp software should have been something easy to pick out of that short list of partitions. Just look for the correct size (about 100GB!)
If that has happened (you chose the macOS partition, instead of the 100GB one that you made in bootcamp, then the macOS is gone.

You will have to start over, erase the drive, reinstall macOS (the Windows install would have wiped that out completely). Get your files and apps from your backup. Run the Boot Camp Assistant again.
Reinstall Windows (watching for the partition screen, so you can choose the size that you used...

 

[WayneColo]

[QUOTE"]If yes, shut your mini OFF.
insert the Mojave installer.
Boot while holding the Option key. Choose the installer from that boot picker screen, and press Return to boot to that.[/QUOTE]

I did that, and the option key and the boot picker came up. option for boo picker comes up,
with the windows and SSD(mojave) options available. I picked mojave and booted into it.
then told it to restart and it booted directly into windows.
then i used your protocol above and get the boot picker again.

I was careful to originally make sure that I put the windows install on the new 100g partition.
and they are both there if I use these steps to get the boot picker window.
Seems really weird, what's happening.
Maybe I should just delete the windows partition and forget this deal. too bad tho.

 

[WayneColo]

thanks, Delta, at least I got this thing booted into mojave again.

 

[DeltaMac]

I think the problem is that installing Windows (particularly after installing the boot camp support software) then set your Mac to boot to the Windows system.
So, you can change that in the Boot Camp utility (available on the task bar where you can choose the icon for other apps).
With that, you can change the boot drive to macOS. (Well, you COULD if you didn't have the Mojave partition, which Windows can't see )
So, how to prevent booting into Windows, then?
ALWAYS use the Option-boot picker screen when you reboot. That assures that you are choosing the correct startup system. You would ALWAYS have to use the Option key when the system restarts, unless you KNOW that is set for the drive you want to use.
Best way forward, is to boot to macOS, open the Startup Disk pref pane. Select your macOS boot system.
Restart should NOW be in macOS. If you need to restart to your Windows system, hold the Option key and select that system.
Because you changed the Startup Disk to macOS, then a simple restart should then boot to your macOS system.