Bootcamp Partition Size Issue

Greetings Taysh83-

I've encountered the same issue, and I'm surprised that this hasn't blown up all over the forums. I don't think it's anything we are doing, or failing to do.

Everything always ran okay when I'd create BootCamp partitions for Windows 10 under MacOS Sierra.

However, when I started using High Sierra Beta, things went a bit awry. I was completing a Windows 10 update but it was going too slow to the point of seeming like it was hanging. I became impatient and mistakenly forced shutdown instead of waiting -- basically bricking my Windows 10 setup.

After properly deleting the partition to start anew, I encountered the same issue;

in my case the only two size options being '-8gb' and '48gb'.

I figured this was part of the trials and tribulations of working with Beta, so I shelved the task until the first full release of High Sierra.

When the release came at the end of September, I attempted once again, and was promptly greeted by the same issue.

FYI, I have already tried everything to pinpoint a fix any issue; i.e. completely wiping down my hard drives (Fusion); installing a fresh copy of High Sierra (instead of restoring from Time Machine) to see if a fresh copy would do the trick; wiping everything and *not* re-creating a fusion drive, to see if it would work straight on one drive alone, etc, etc. It did not matter. So I wiped everything yet again, and decided to restore from Time Machine and continue working for the time being.

I contacted official Apple Support last week, and spoke with several advisors up the chain. I received the attention of several Senior Advisors who had me compile severals logs to submit.

My last conversation with them was earlier this week:

They are aware of this bug (it seems to be affecting a decent number of users) and was told they are currently working through it;

That a fix will be forthcoming in the form of either either app store Software Update, or possibly through some other steps the user will need to undertake. They have assured me they'll remain in touch to update on when - and through which method - the fix becomes available.

I figured I write this out and share here for anyone else encountering this same issue.

OK everyone I figured how this problem is.
I tried a several solution and I reached to one!
I tried to format the Mac OS High Sierra to the main system (lion 10.8) then install high Sierra again. but, partitions didn't work . so I formatted again and installed the previous system macOS Sierra and now it's work fine . so the x high Sierra system x doesn't support the divide ability or there is a technical mistake on the high Sierra.

High Sierra has a broken BC Assistant because it assumes that you have APFS, not HFS+.

Can you How to choose a startup disk on your Mac - Apple Support and install Sierra on an external disk, boot from it, run BCA and partition the disk?

The other option you have is to create a FAT partition manually, create a Hybrid MBR using GPT FDisk (GPT fdisk download | SourceForge.net) and use the the built-in Optical drive (if you have one) to install W7.

--I should add a few more points:

-After repeatedly resetting SMC & PRAM, that does nothing to fix the BCA partition issue.

-'Divide Equally' does nothing but toggle between the two strange size options provided. That is if it's not greyed out entirely.

-For anyone curious, I did at one point decide to try the positive sized option (48gb, in my case), to see if the BootCamp Assistant would work. And it did successfully create the partition and continue fully through the Windows installation steps. The partition was much too small for my needs though and I simply deleted it.

There are a few work-arounds I considered but after spending numerous hours troubleshooting I decided enough was enough, and it was at that point I decided to properly report the issue to Apple Support and move towards an official fix, only because I can afford the wait really.

If I were in more of a pinch I'd take the extra effort and extra hours to do. If anyone is in a pinch and NEEDS a properly sized partition ASAP, here are my thoughts---

Option 1 (Recommended, if possible, as it does not require extra steps running any third-party apps under Windows):

-Fully back-up your MacOS system (Required, as following steps include destructive processes);

-Get your hands on a MacOS Sierra Installer. I always keep copies of my previous installers for the reason of ever needing to use an older OS. I don't know how easy or difficult it might be for get a hold of an older installer, and for a macOS that provides BootCamp support for Windows 10... MacOS Sierra certainly does..;

-Create a bootable os Sierra install USB (using Terminal, or DiskMaker, Etcher, or any appropriate boot disk creator);

-Wipe your drive and perform a fresh install of Sierra (using Recovery; Cmd+R on boot);

-Once in your fresh install of Sierra, go to Boot Camp Assistant and go through necessary steps to create Windows partition with the size of your choosing;

-Install Windows 10 (Anniversary, *not* Creators) etc, etc;

-Go back into Recovery mode once again - leaving Bootcamp partition alone -

Delete & Time Machine Restore your Mac OS volume back to how it was.

Option 2 (Have never personally tried it, since it means re-sizing a Windows partition after the fact; a frightening waste-of-time-headache for me if something didn't work as required. But, worth exploring if having an older installer under option 1 is a no-go):

-Fully Back-up your MacOS volume (optional, but *HIGHLY* recommended. If something goes wrong..........)

-In High Sierra, go ahead and pick the positive-sized of the two weird size options provided by BootCamp Assistant;

-Continue & successfully install Windows 10 (Anniversary Update, *not* Creators);

-Research and find a reputable Windows Partition re-sizing app, and follow all directions to increase Bootcamp partition size;

(This last step is what I've never bothered to do, so make sure you find a good method and app with solid instructions).

Bonadventure's solution here how to resize my bootcamp partition without deleting itit seems to be quite reliable, having worked for many people. Seems like there are numerous YouTube tutorials as well. I would just patiently comb through to make sure I have a solution that seems reasonable, reliable, properly laid out & explained in detail.

Start Applications -> Utilities -> Terminal and run

diskutil list

A hybrid MBR can be created as shown in the Rebuild MBR section of El Capitan has deleted my bootcamp windows partition using GPT fdisk download | SourceForge.net .

Just thought I'd record my experience here. I was having the same exact problem with not being able to select the partition size in Boot Camp Assistant. I tried everything here, everything I could find in other forums, and called Apple support and tried what they said (in fact they were suggesting it might be a problem with my hardware / hard drive); nothing worked.

What I finally figured out was this is a problem in Mac OS High Sierra.

The only way I was able to finally get this to work was to downgrade to original "Sierra" and setup Bootcamp from there, then re-upgrade to High Sierra.

These were my basic steps:

(proceed with caution / at your own risk- you are wiping out all your original data, so have a good backup first!)

• Make a Time Machine backup of my mac.
• Download and create an install disk (on a USB stick) of the previous Mac OS "Sierra"
• Boot from the USB stick
• Use Disk Utility to remove ALL partitions on my Hard Drive (getting rid of the High Sierra recovery drive as well- this is important)
• Create and format a new single Mac OS Journaled partition
• Exit Disk Utility, then select Install Mac OS Sierra
• Reboot into freshly installed Sierra
• Go straight to Boot Camp Assistant, follow the steps to create the new partition, and go ahead and do the Windows install (I did this with Windows 10 Pro)
• After Windows install is complete, boot back into Sierra and start up the Migration Assistant
• Plug in your Time Machine backup hard drive and migrate your old data back over.
• Then you can go into the App Store and upgrade back to High Sierra, with everything back as it should be.

( Just an observation: One of the things I noticed is the Sierra installer & BC Assistant would report/recognize my full hard drive size (2TB) but the High Sierra installer & BC Assistant would always report it as 1.8TB. High Sierra seems to store its recovery partition differently then Sierra, creating a separate hidden 200GB recovery partition. Perhaps the Boot Camp Assistant can't see past / choose the correct partition in its partitioning tool, and it's trying to split up the already full, hidden 200GB recovery partition by mistake? But what do I know?? Fix it, Apple!! )

If you purchased an older macOS version from App Store or any of your Macs came with Sierra or older macOS (El Capitan or Yosemite), the Internet Recovery console can provide you with the ability to re-install it on an external drive. Local Recovery will only offer the currently installed macOS version.

Were you ever given an update on the solution for this? I'm about to go through with option 2 as I do not have an older version of OS X immediately available to me and just got done with a full disk format and fresh install after trying, unsuccessfully, to repair my broken partitions from several previous attempts.

Greetings lastevens--

In point of fact I have not received anything in way of a solution.

I reached out generally to Apple last week which led nowhere, and I'm about to reach out to my assigned point-of-contact one final time today before having to do something myself.

I continued doing a little more thorough research after posting my previous posts and found that my concerns with my 2nd Option above are not completely unfounded;

Apparently after using a Windows partition re-sizing app, some people have encountered issues down the road (relating to subsequent updates and eventually in some cases the very visibility of the partitions themselves).

To me it simply means keeping regular backups of everything, and being prepared to deal with future possible issues.

Good luck to us all facing these issues!

Definitely an issue with High Sierra. I had the exact same problem...

Backed up to Time Machine, did a OSX Restore (Command R at boot) and re-installed Lion (which it defaulted to -- 2012 Mac Mini). Installed bootcamp while in Lion -- partitioned properly this time.

Restore from Time Machine.

I'm sure this issue is from last update of mac (high sierra).
- actually before few week ago there is some update came i do it.
Before i had a partition already on mac sierra and there isn't any problem but the new update came and i updated that. so after few days i formated my mac because of slow problems... but it's on high sierra that's why !
Apple should solve this because i don't have a good internet to format the mac again and again and again to try to solve this problem on my own. somebody up mention that he fix it on lion ( if i read that before one day i could make partition before i updated it to high sierra again ).