Recently I’ve tried to upgrade the operating system on my Macbook Pro to the newest OS, MacOS High Sierra. I downloaded the installer directly from App Store and when it comes to the installation process, I got this problem.
It stuck and won’t continue, there’s a message like this : This partition map modification would make a Windows partition unbootable. The option is continue and restart again. When I clicked continue, the installer loads again, same error message. Basically I’m stuck in a loop.
I tried to cancel the installation, but it didn’t fix the problem. Lucky me finally I’ve got the solution from the Apple discussion site. Althought it has to reformat one of my partition disk.
For the information, I used three partitions on my Mac. One for Mac OS X Snow Leopard, one for the Sierra and one for Windows 7.
To fix the error problem, I have to erase and delete my Boothcamp/Windows partition, I have to decide it. That because High Sierra may convert the disk to Core Storage that only permits two partitions on your disk.
So I have to restart my Mac and enter to my Snow Leopard partition by hold the option when rebooting and begin to delete my Windows partiton with disk utility.
After there are only two partitions left, I tried to enter my Sierra partition and it started to load the installer again and it worked.
Now I can running High Sierra without problem, althought I have to loss my Windows. I think it’s fine, because I still can to reinstall it again if I want. Perhaps this experience will help you guys if you get same problem.