Can't upgrade to OS Sierra

To state it more correctly (with a very watered-down explanation): OS X is a Unix descendant. Many non-alphanumeric characters have special meanings and functions, depending on their usage context. They're called "metacharacters". Unix is very exacting about how they're interpreted. There exists no prohibition against using them, for example, in file names. BUT you're at risk that scripts or programs that access the files don't necessarily follow best practices to ensure the metacharacters are handled properly. You're just safer not using them in file names.

Hi Tommyweather,

Thanks for posting in the Apple Support Community! I understand you're unable to update your MacBook Pro to macOS Sierra because you're getting an internal error. I always like to make sure I keep my Mac up to date with the latest software, so I can understand wanting to make sure you're able to update your Mac too. I'm happy to offer some suggestions.

Before going through any troubleshooting steps, I recommend to backup your data using Time Machine. The steps that I'm going to recommend shouldn't erase any of your data but it's always a great idea to make sure your data is safe.

Use Time Machine to back up or restore your Mac

The next thing that I recommend doing is trying to repair your hard drive using disk utility. It's possible an error on the hard drive could cause the error you're getting. You can use the following section of this article for help with that:

Try Disk Utility

Use these steps to use the Disk Utility app to verify or repair a disk.

1. If you're using OS X Lion or later, start the computer from Recovery System or Internet Recovery. If you're using an older version of OS X and your computer came with a Mac OS X Install disc, insert the installation disc and restart the computer while holding the C key instead.
2. When your computer finishes starting up, choose Disk Utility from the Utilities window, or from the Installer menu if you're started from an installation disc.
3. Click the First Aid tab.
4. Click the disclosure triangle to the left of the hard drive icon to display the names of your hard disk volumes and partitions.
5. Select your Startup Disk (usually named "Macintosh HD").
6. Click Repair. Disk Utility checks and repairs the disk.

Tip: With Mac OS X v10.6 and earlier, always start up your computer from an Install or Restore disc when using Disk Utility to verify or repair your startup volume. Otherwise, you might see some disk error messages.

Resolve startup issues and perform disk maintenance with Disk Utility and fsck

Once you've confirmed that your hard disk is working normally, try installing the update again. If you're still running in to an error, reply back and let us know during which part of the installation you're seeing that error.

Cheers!

Not the OP but also suffering from the same problem as described over in this thread: Re: macOS Sierra installation (from El Capitan) fails with "Internal error" message

One of the things I did try during my second installation attempt was using Disk First Aid from the recovery partition exactly as described here. It did not resolve the problem.

Interestingly enough, yes I do. I have an SSD boot drive called "OS & Apps". This might be worth a third attempt...

Good point! UNIX dislikes some characters in filenames. Try to avoid using punctuation and symbols as much as possible.

And guess what, that's it. Renamed "OS & Apps" to "Startup" and the install succeeds. Thanks very much!

Regarding Unix & filenames, Unix is actually very tolerant of symbols, as is OSX and there is no legitimate reason this should be a problem. The problem here is likely missing quoting or escaping in a shell script executed during the install - as characters like & have special meaning to the shell.

Hello!

I have a Macbook Pro Mid 2010, for the past weeks its been asking me about Upgrade to Sierra, one night I close the Mac and on the next day BOOM Thanks apple, now my notebook wont complete the upgrade that I never ask or agreed and it wont go back to the OS X El Capitan.

If anyone know how to fix this without losing all my information please, since Im not in the US now I cant take it to an Apple store, and when I use system utilities it wont download the OS X El Capitan.

Any help please.

What year is your MacBook Pro? See compatibility chart from Apple's keynote.

It needs to be 2010 or later.

Removing the ampersand ( & ) worked for me after trying all the other standard recommendations.

Strange it would become a problem on this update and not years earlier.

Good to see that there is still something incredibly simple to frustrate you for hours with computers!

Thanks to posters for solving it.

Hi Tommyweather,

I also had an issue installing the new macOS Sierra and couldn't do it myself. At least I wouldt come up to the solution myself, if I wouldt have contacted apple.

The solution was: the Volume, that you have to click to install the macOS on, does it contain any special charachter i.e. " § $ % & / ( )"? My Volumes name was R&M HDD, so the "&" caused problems while updating. I talked to apple support and thats the first thing they asked. Now I did updates before with my previous devices, and it was never an issue. Apple said, that they have a Ticket to this issue and are going to solve it.

This could be the issue with your device aswell?

Greets

Hi, I'm not able to install Sierra because it says its not supported. From what I've read so far, since my Mac is OS X 10.9.5 it should be able to deal with Sierra. It's not an internal system error, it just won't let me download it from the app store at all ... Any tips what I should do? Does that Disk Repair run-through apply to this issue?

I've been having this same issue too. Has Apple contacted you about a solution? I tried the Disk Repair and it was no help.