Will upgrading Windows 8 to 8.1 affect Ubuntu?

It's a rather simple question (I hope). I currently have Windows 8 and I am dual booting it with Ubuntu 13.04.

If I were to install the latest update for Windows 8, that being 8.1, will it affect Ubuntu or will there be any conflicts between the two?

While an installation from scratch will overwrite the MBR an upgrade from Windows 8 to 8.1 shouldn't. I've scoured the net in search for supporting facts, but found only this post which looks more like a piece of opinion (like mine) than anything.

In any case: Should the MBR still be overwritten by an upgrade, you can still repair the Grub2 MBR without much trouble.

I updated from Windows 8 to 8.1 and can confirm that this update WILL overwrite the MBR. I am now greeted by the grub rescue screen.

I can confirm that my laptop is greeted with GRUB Rescue Screen. Yes, I too had same windows 8 and ubuntu 13.10; After Updating window 8 to windows 8.1, i am Unable to boot into Ubuntu I have resolved via How can I repair grub? (How to get Ubuntu back after installing Windows?) by running Boot repair!

The upgrade from 8 to 8.1 worked great for me. In addition, if I choose to set the Windows bootloader as the first (default) option, every time I boot or restart the computer there is now a new blue screen that looks like the screen you see with the "Advanced Startup" screen that first appeared in Windows with Windows 8. From this screen, there was an option to continue booting to Windows 8.1, Boot to Linux Mint 15, or boot with EFI USB. Surprisingly enough, when I selected the Linux option, I was greeted by the GRUB menu. Since I'm seeing this blue screen any time I boot or reboot to Windows, I just made the Windows bootloader the default option. That's a whole lot easier than it was before with Windows 8 and all the frustrations with the BCD, boot-repair, rEFInd, etc. Trivial bonus: you can use the mouse/cursor on that blue startup screen as well. Here's a quick picture I snapped of the sceen:

I also just upgraded to Windows 8.1 from 8 and GRUB was just fine, didn't need to do anything other than be on alert so that I would choose the Windows option in GRUB the two times the PC rebooted during the whole process. So there you have it, you can't be sure what's going to happen.