I wanted to allocate more space to the Windows side by using Disk utility in macOS. So I partitioned a new part. I would then jump to windows and allocate that new untitled partition to Windows, but I can't get back to Windows. Is there a solution to this? I'm fine with reinstalling windows if thats an option. However, I would like my windows key, if that is possible. I followed this video https://www.youtube.com/watch?v=zhkdOLXT6Eg.

Operating System: Sierra 10.12.6

I also looked at this post, but I can not figure out what to do.

Mac won't boot Windows partition after using disk utility


  • It would be helpful in to include the model/year of your Mac. Did you use the Boot Camp Assistant to install Windows? Did you install Windows 10 or first install an older version of Windows and then upgrade to Windows 10? Commented Apr 2, 2020 at 13:02

2 Answers 2


You will need to boot into Windows to access the recovery key. Do you have the T2 security chip? If so, try disabling Secure Boot. Apple doesn't recommend resizing the Bootcamp partition so that might be the issue.


If Windows was installed using the Boot Camp Assistant, then neither Apple nor Microsoft offer a practical way to increase the Windows partition, other than remove and reinstall Windows.

The Boot Camp Assistant will only install Windows 10 on the newer Mac models. If you have an older model, the Boot Camp Assistant may still be able to install an older version of Windows. Afterwards, you may be able to upgrade to Windows 10.

If Windows 10 is activated, then you do not need the product key to reinstall or upgrade. However, if you first reinstalled an older version of Windows (XP, Vista, 7, 8 or 8.1), you may need the product key for the older version.

In your question, you stated you partitioned. If this was successful and Windows does not boot, then you probably have Windows installed to BIOS boot. An effort could be made to try an make Windows bootable. There may be no point in trying, if you are going to reinstall Windows anyway. This a decision you will have to make.

If you have an older model Mac and the Boot Camp Assistant will not let you install Windows 10, then it is usually possible to install Windows 10 without using the Boot Camp Assistant. The instruction depend on your model Mac.

I should mention there are third party tools that can aid in enlarging the Windows partition without the loss of data. WinClone is one such product.

Comment about the Linked Video

The video is a deliberate attempt to deceive the viewer. At the time the video was made the Boot Camp Assistant only installed BIOS booting Windows. This required using hybrid partitioning. The MiniTool Partitioning Wizard does not properly handle hybrid partitioned drives. Specifically, the Wizard correctly updates the MBR partition table, but fails to update the Guid Partition Table (GPT). The video is fraudulent and anyone with experience can easily see this. At time mark 1:46, free space is created between the OS X partitions and the Windows partition. At time mark 2:40, the free space can be viewed as occurring after the Windows partition. So, at some point not shown in the video, changes were made. At time mark 3:15, the Windows partition is extended. In fact, the Windows partition would also need to be moved to be beginning of the free space created at time mark 1:46.

Comment about the Linked Question

I would advise not to follow any answers to a question that were not accepted by the OP and have comments that indicate none of answers worked.

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