Sierra frozen at login screen - keyboard and mouse unresponsive

Question

After rebooting my MBPr, it is now frozen at the login screen showing the list of users. I'm unable to move the cursor or use the keyboard. Booting in safe mode does the same thing. A few days ago, I updated Sierra to 10.12.4, so it might be related to that. Right before the problem happened, I was pruning old third-party Launch Agents and Daemons, but I did not delete any from Apple. That might be related, but I don't know for sure, since I very rarely reboot the computer.

I reset NVRAM.

I deleted /Library/Preferences/com.apple.loginwindow.plist.

I used Disk Utility in recovery mode to repair the startup disk, but no problems were found.

I looked at /var/log/system.log using Terminal in recovery mode, and I see many lines related to Installer, so is it trying to install something, or is this a normal part of recovery mode?

Small sample of the log is below, and the full log is on pastebin. Sierra's new log command doesn't work from recovery mode.

May 15 16:10:08 MacBook-Pro Installer Progress[151]: Register process 491, phaseName Install Springboard, uuid 35F782F8-715E-41FF-9AF6-DB016B483C68
May 15 16:10:08 MacBook-Pro Installer Progress[151]: Connected processes = {
        "35F782F8-715E-41FF-9AF6-DB016B483C68" =     {
            "Phase Name" = "Install Springboard";
            "Process ID" = 491;
            UUID = "35F782F8-715E-41FF-9AF6-DB016B483C68";
        };
        "A9879B21-4872-49FC-AC94-E8F7985A5F61" =     {
            CompletionHandlerKey = "<__NSMallocBlock__: 0x7fe35dcf0580>";
            "Phase Name" = "Language Chooser";
            "Process ID" = 468;
            UUID = "A9879B21-4872-49FC-AC94-E8F7985A5F61";
        };
        "D963D32E-BA49-4ADD-8359-79B93262F438" =     {
            CompletionHandlerKey = "<__NSMallocBlock__: 0x7fe35b70eb50>";
            "Phase Name" = "Launch Progress Window";
            "Process ID" = 465;
            UUID = "D963D32E-BA49-4ADD-8359-79B93262F438";
        };
    }
May 15 16:10:08 MacBook-Pro Installer Progress[151]: Saving completion handler for phase Install Springboard
May 15 16:10:08 MacBook-Pro Installer Progress[151]: The Progress UI has been hidden
May 15 16:10:08 MacBook-Pro Installer Progress[151]: Saving completion handler for phase Install Springboard
May 15 16:10:08 MacBook-Pro Installer Progress[151]: Unregister process 491, phaseName Install Springboard, uuid 35F782F8-715E-41FF-9AF6-DB016B483C68

I appreciate any advice, but if you simply tell me to reinstall MacOS, I will downvote the answer, because I want to actually find the problem.

Answer 1

Booting to Single User Mode showed some valuable troubleshooting information. It turns out I had some bad third-party kexts installed in /System/Library/Extensions. Removed those and now all is well.

Answer 2

I've had this happen a couple of times after messing around with betas, cloning from one machine to another, or after "awkward" updates (where things don't seem quite right after the update finally finishes). It is usually fixed by resetting the SMC (which is different than zapping PRAM/NVRAM).

From an OSX Daily Post:

This is how to reset SMC on most modern Mac laptops, none of which have a removable battery:

• Shutdown your MacBook Air / MacBook Pro
• Connect the power adapter to the Mac
• On the MacBook / Pro’s keyboard, hold down the Shift+Control+Option keys and the Power button at the same time
• Release all keys and the power button at the same time – the little light on the MagSafe adapter may change colors briefly to indicate the SMC has reset
• Boot your Mac as usual

Here’s the key sequence to hold down:

Reset the SMC of a MacBook Air or Retina MacBook Pro

Do keep in mind that by resetting the SMC you will lose power specific settings, like the time it takes to sleep a Mac and other customizations to power settings. No big deal, but if you have made many changes to your hardware behavior you will want to adjust stuff like sleep behavior again.

The boot time after resetting a machines SMC can be a bit longer than usual, that is normal.

It looks like you've used recovery mode to do disk repairs. I suspect Recovery mode is loading a different copy of the drivers than your main partition, which is why it works there but not in Safe Mode and "normal" mode.

If your concern about reinstalling (should the SMC reset not work) is that you don't want to risk losing data or having to start from scratch, a reinstall from recovery mode won't wipe the disk or mess up your account. Everything will be there like it should be when it's done. I've done that several times too.

You could also try remoting in from another machine using VNC or Screen Sharing, presuming you have those set up, or have SSH enabled so you can log in and kick start Apple Remote Desktop.

Answer 3

It may be to do with your Login Password. Here's the fix -

• Hold CMD+R when start-up until grey screen and apple logo appears. Wait a few minutes until it enters recovery mode.
• Click utilities and select terminal.
• Type resetpassword and press enter. Close the terminal window and behind that you will find the Reset Password Utility.
• Select User account and enter a new password or leave blank and click save.

Then just simply restart from the apple menu and login with your new password.

Should log in now with no freezes.