It seems every version of Mac operating systems that you install may have a few issues that pop up. Now, we’re not saying you can expect to experience all or even any of the issues we outline here. In fact, the vast majority of users upgrading to macOS Sierra won’t have these problems.
But if you do experience an issue after upgrading, it’s probably going to be one of the issues we mention here. Not to worry; we’ll show you how to resolve it.
macOS Sierra Freezes During Install
There are two common freezing issues; one can occur during the install process, the other when your Mac reboots after the install is complete.
Freezes After Restart: Let’s start with the easier of the two issues to fix: when your Mac seems to stall during the final reboot of the installation. At this point, you’ve selected the target drive for the Sierra install, agreed to the licensing, and your Mac was displaying a progress bar with an estimate for time remaining.
The screen goes black, and your Mac reboots. So far, so good. The next step is for your Mac to finish the restart and display the Setup Assistant, for finishing up any needed details before the login or desktop is displayed. Instead, your Mac seems to be frozen on the dark screen, or perhaps with a wait icon spinning away.
The problem is that your Mac failed to restart correctly, but because all the install guides warn you that the first restart can take a long time, you don’t know how long to wait. To be on the safe side, a half hour is more than long enough, and if your Mac hasn’t brought up the Setup Assistant by then, you can give your Mac a figurative kick in the pants.
Force your Mac to shut down by pressing and holding the power switch. After your Mac shuts off, you can go ahead and power it up again. Your Mac should power on and display the Setup Assistant, letting you finish the installation of macOS Sierra.
Crashes While Installing: This is slightly different than freezing after the restart. In this case, your Mac spontaneously crashes during the installation, usually just after you start the install process. The cause is usually antivirus apps that weren’t disabled before starting the install. You’ll likely have to restart your Mac in Safe mode by holding down the shift key when starting up. Once you get to the desktop, disable your antivirus app and then restart.
Once you restart normally, confirm that your antivirus app is disabled, and then begin the macOS Sierra installation process again.
Slow or No Wi-Fi
After you finish the upgrade to Sierra, you may notice that your Wi-Fi connection is no longer working, or if you’re able to connect, the Wi-Fi connection seems very slow. You should first check basic Wi-Fi configurations, such as whether you’re connecting to the correct Wi-Fi channel or band, connecting to the correct network, or using the correct password.
An easy way to gather all the Wi-Fi settings is to option-click the Wi-Fi icon in the menu bar.
Some users have seen their Macs trying to connect to a different Wi-Fi network, usually because the other network has a stronger signal.
Once you’ve gone through all the Wi-Fi connection settings and it hasn’t fixed the issue, then it’s time to dump your current Wi-Fi preferences and start from scratch.
Delete Wi-Fi Preferences
After you check your Wi-Fi settings and are unable to correct the connection issue, you can try deleting the Wi-Fi preference files and then setting up a new Wi-Fi connection.
WARNING: Deleting these files means you’ll have to set up your Wi-Fi connection again from scratch. Be sure to have any necessary information handy, such as network name, password, and DNS settings (if needed).
Turn Wi-Fi off by selecting Wi-Fi Off from the Wi-Fi icon in the Apple menu bar.
Open a Finder window, or click on an empty area of the desktop.
From the Finder’s Go menu, select Go to Folder.
In the ‘Go to the folder’ sheet that drops down, enter:
and then click the Go button.
A new Finder window will open, displaying the contents of the SystemConfiguration folder.
Locate the following files and drag them to the trash.
Click the Wi-Fi icon in the Apple menu bar and turn Wi-Fi back on.
This will cause an entirely new set of Wi-Fi-related preference files to be created. You should now be able to connect to your Wi-Fi network; have your password handy.
Time Machine Not Working
If you’re a Time Machine user, you may have noticed problems with Time Machine’s ability to complete a backup. There have been various solutions offered by the Mac community, including erasing the Time Machine drive and starting over again.
That’s a solution for when all else fails. But first, give this fix a try:
Spotlight may be running a new index of the startup drive after an update to macOS Sierra. Indexing can take a long time, and is known to interfere with many apps, including Time Machine. In many cases, the simple solution is to turn Time Machine off, and wait for the first index to complete.
Launch System Preferences and select the Time Machine preference pane.
Remove the checkmark from the Backup Automatically item.
To check whether Spotlight indexing is complete, click in the Spotlight menu bar item, and enter some text in the Spotlight text field; any text will do. If a progress bar is shown, then indexing is still occurring. If no progress bar is displayed, then indexing has completed.
Don’t forget to turn Time Machine back on once indexing is complete.
If Time Machine Still Isn’t Working…
Apple suggests performing an SMC reset and then a PRAM/NVRAM reset, in that specific order, to get Time Machine working correctly. You can find out how to perform the two resets in the Rocket Yard Guide on How to Reset NVRAM, PRAM and SMC on Your Mac. Don’t forget the order: SMC first, then PRAM/NVRAM.
Apps Can’t Be Opened
If you see a message that an app is damaged and can’t be opened when you try to launch it, the usual fix is to delete the application and download a fresh copy from the Mac App Store. However, if you’re seeing this message just after installing macOS Sierra, you may want to try these tricks first:
Hold down the option + command keys when launching the app. This keyboard combination is usually used to hide all other open apps, but in this case, also seems to allow some damaged apps to launch successfully.
If that little trick doesn’t work, then deleting the cache files used by the app will usually get things working again.
Open a Finder window, or click on the desktop.
From the Finder’s Go menu, select Go to Folder.
In the dropdown sheet, enter: ~/Library/Caches
In the Finder window that opens, locate the folder that includes the name of the app you’re having problems with. Most of the folders will have names like com.developersname.appname. So, for example, if you’re having problems getting Messages to launch, look for the folder named com.apple.messages.
Open the app’s folder and delete all the items within it.
Clear the PRAM/NVRAM as mentioned above, then try launching the app again.