Can't boot into Bootcamp after 10.11.2 update

I have just installed the 10.11.2 El Capitan update on my Mac. After this has installed and the machine rebooted I can no longer boot into Windows.

It shows up in "Startup Disk" and I can select it from the boot menu on my Mac. When I select it, I just get a blank grey screen.

I can access the Bootcamp partition in OSX and all the data seems to be intact. I guess the OSX update has done something with the boot record for the Windows partition. Any idea how to fix this?

Funnily enough, this happened to me before. I resized my windows partition about a year ago and the same thing happened. I managed to repair the boot info, but for the life of me I can't remember what I did.

What is the year and model of your mac? Also what version of Windows?

I did find this article that I found interesting. It says apple decided with the new upgrade to bootcamp that macs over 3 years old can not handle running Windows 10. Since I am currently running 10.11.2 on a 2009 Macbook and it has a bootcamp partition that has Windows 10 on it, I am wondering just how valid the article is. But I guess it is possible that the recent update messed your Windows install.

Lisa

It is a 2011 iMac. I've been running Windows 10 on it since launch though.

If Apple won't support Windows 10 that is one thing, if they proactively disable the ability to run Windows 10 it would be the last time Apple got a penny from me.

The article is from some mob named myce so just ignore it. You are living proof they are wrong Lisa! I certainly have never learned of myce. (Neither has my spellchacker which insists they are mice).

I thought as much Harry but I thought I might have missed something and I was just a fluke. Still - any ideas for the OP? I updated El Capitan twice now and my W10 install is fine. Something else is going on.

Lisa

I've ended up deleting the Bootcamp partition and starting again. I've hit an obstacle though, Bootcamp has been stuck partitioning for about two hours. It is progressing, but really slowly. I don't want to force quit such an activity.

I did check the SMART status of the HDD and it passed beforehand. The HDD appears to be healthy (if old). I also ran the test from SMART Utility on the drive as well and it passed.

Did you use BootCamp Assistant to remove the first BootCamp partition?

Yes, I did. It managed to complete in the end. Although I got an error message about the Windows disk not being in. Bootcamp Assistant then closed.

I was left with a Bootcamp partition but nothing on it. I deleted the partition and tried again. It repartition much quicker this time (in about 2 mins). Then the machine rebooted and stuck on a grey screen. I could reboot and load the boot manager, it recognised the Windows CD and also a UFI boot CD?

I have a separate Windows 10 USB which is bootable. I can boot from this, Windows Install starts but it won't install on the Bootcamp partition. It gives an error about an MBR and a GPT on the partition.