Updated to 10.9.3 but now can not boot, will boot in safe mode only ...? Any ideas?.

Hi Captaindaylight,

Welcome to Apple Support Communities!

It sounds like you Mac may be starting up to a gray screen since updating OS X, unless you Safe Boot it. The article linked below has some great tips that will help you resolve the issue.

Mac OS X: Gray screen appears during startup

http://support.apple.com/kb/TS2570

Perform a Safe Boot

Simply performing a Safe Boot may resolve this issue.

1. Shut down your Mac. If necessary, hold your Mac's power button for several seconds to force it to power down.
2. Start your Mac, then immediately hold the Shift key. This performs a Safe Boot. Advanced tip: If you want to see the status of a Safe Boot as it progresses, you can hold Shift-Command-V during start up (instead of just Shift).
   
   Note: A Safe Boot takes longer than a typical start up because it includes a disk check and other operations.
3. If your Mac starts up as expected, immediately try restarting.

If the Safe Boot does not work, or the restart after a successful Safe Boot does not work, go to the next section.Reset the NVRAM / PRAM

1. Shut down your Mac. If necessary, hold your Mac's power button for several seconds to force it to power down.
2. Reset the NVRAM / PRAM.

If the gray screen issue persists, go to the next section. Start from your Mac OS X Install disc; use Disk Utility

1. Insert your Mac OS X 10.4 or 10.5 installation disc (if you have discs with both versions, use whichever is closest to the Mac OS X version installed on your Mac; do not use a startup disc which came with a different Mac or which contains an earlier version of Mac OS X).
2. Shut down your Mac. If necessary, hold your Mac's power button for several seconds to force it to power down.
3. Start up your Mac while holding the C key to start from the disc.
4. Once started from the disc, choose Disk Utility from the Utility menu.
   Note: If the gray screen issue persists and you can't start from the disc, go to the "Disconnect peripheral devices" section.
5. In Disk Utility, perform a disk repair of your Mac OS X volume; if no issues are found, perform a permissions repair as well. If issues are found during the disk repair, try repairing again.
6. After the Disk Utility operations are complete, restart without holding any keys.

If the gray screen issue persists, go to the next section. Check your cables and power sourceMake sure your power cables are secure (especially if you use a desktop Mac). Try a different cable or outlet if possible. If you use a surge protecter, try connecting directly to an outlet as a test.If you have power-related issues (such as your desktop Mac shutting down or restarting, or room lights dimming when an appliance comes on, consider contacting a certified electrician to check your outlets and electrical wiring).If the gray screen issue persists, go to the next section.Remove third-party RAM and internal hardware
Remove any non-Apple RAM or other third-party hardware upgrades (such as expansion cards or third-party optical drives or hard drives, if present) to help isolate the issue. This is necessary to get as close as possible to the original factory hardware configuration of your Mac.If you are not sure which RAM modules or other hardware is Apple or third-party, or if you are not comfortable performing these steps, or if you have a Mac mini, consider contacting an Apple Authorized Service Provider for assistance. Otherwise, perform these steps before going to the next section.

1. Shut down your Mac. If necessary, hold your Mac's power button for several seconds to force it to power down.
2. Open your Mac to access the memory slots. Refer to the User Guide that came with your Mac, or search Apple Support Manuals for a PDF copy of your Mac's User Guide.
3. Remove any third-party RAM that has been installed.
4. Reinstall the Apple RAM that came with the computer if available. Note that Mac OS X 10.5 requires 512 MB or more of RAM; Mac OS X 10.4 requires 256 MB or more of RAM.
5. If your Mac starts up with only Apple RAM installed, contact the vendor of your third-party RAM.

If you have installed a third-party drive, ensure it is running the latest firmware. Otherwise, reinstall the Apple drive that came with the computer if available. If the gray screen issue persists, go to the next section. Perform an Archive and Install installation of Mac OS XIf the above steps do not resolve the issue, and you can successfully start from your Mac OS X Install disc as noted above:

1. Insert your Mac OS X 10.4 or 10.5 installation disc (if you have discs with both versions, use whichever is closest to the Mac OS X version installed on your Mac; do not use a startup disc which came with a different Mac or which contains an earlier version of Mac OS X).
2. Shut down your Mac. If necessary, hold your Mac's power button for several seconds to force it to power down.
3. Start up your Mac while holding the C key to start from the disc.
4. Perform an Archive and Install installation (preserving users and network settings).

After installation, if the gray screen issue persists, go to the next section. Perform an Erase and Install installation of Mac OS X as a last resort
Important: You should only perform this step after trying all of the above steps. This process will erase all files from your Mac OS X volume. If possible, back up important files first, or use Time Machine. You may be able to connect your Mac to another Mac with a FireWire cable and FireWire target disk mode, in order to try to manually back up files. Alternatively, you may wish to make an appointment with a Mac Genius at an Apple store, or contactan Apple Authorized Service Provider for assistance.To erase your Mac OS X volume and reinstall Mac OS X:

1. Insert your Mac OS X 10.4 or 10.5 installation disc.
2. Shut down your Mac. If necessary, hold your Mac's power button for several seconds to force it to power down.
3. Startup your Mac while holding the C key to start from the disc.
4. Perform an Erase and Install installation of Mac OS X.
5. After installing, starting from your Mac OS X volume, and verifying the issue is resolved, you should use Software Update to update to the latest available version of Mac OS X.

Additional Information

If the issue persists after you follow the above steps, you may wish to make an appointment with a Mac Genius at an Apple store, contact AppleCare via phone, or contact an Apple Authorized Service Provider for assistance.If the issue only occurs when multiple peripheral devices are connectedIf a gray screen appears during start up only when several peripheral devices (that is, USB and/or FireWire devices) are connected, and you don't want to have only one device connected at a time, the issue may be caused by a combination of the peripheral devices.To illustrate this hypothetically, you may have three USB devices, which we'll call "A", "B", and "C". The issue may be that peripherals A and C have a conflict of some sort, and a gray screen only appears if they both are connected, but not if each one is connected separately. In the above "Disconnect, test peripheral devices and network cables" section you may have inferred that you have an issue only with device C because it was added after A. To avoid an inaccurate analysis, connect device C to your computer with no other devices. If your Mac has the startup issue with only device C connected, then you know it is the source of the issue. However if your Mac starts up, you have a conflict of devices to work out. To do this add the other devices one at a time with device C connected until your startup issue occurs (restart after adding one device). Repeat this process until you have just the minimum set of devices to produce your startup issue.What can you do?

• You should make sure each device has the latest firmware installed if applicable--check with the manufacturer for more information. You should also check for the latest driver versions, and if necessary install them while started in Safe Mode per above.
• If any of the devices requires a separate power source, be sure that power is connected to the device (for example, even if a device appears to be powered when connected via USB without the power cable, connect its power cable).
• Try different USB or FireWire cables with each device, as applicable.
• If you have a device similar to one of the conflicting devices, try replacing it with another one.
• Contact each device manufacturer or the materials that came with the device. for more support information or, if needed, service options.

-Jason

Jason - I'm sorry to point this out but after a 'simple' software update a user should not have to jump through these ridiculous hoops.

I too am seeing the same issues which Captaindaylight is seeing. I did nothing to my system this morning other than update to 10.9.3 and now I can only boot via safe mode. Otherwise I get a blank gray screen.

Is there a way to un-install the latest update or is there a known issue thread you might be able to direct us to which is more helpful than the boilerplate safe mode / Reset the NVRAM / PRAM cycle?

Thanks.

Edit - more info about my Mackbook Air.

13 inch 2012

Processor 1.8 GHz Intel Core i5

Memory 4 GB 1600 MHz DDR3

Graphics Intel HD Graphics 4000

Software OS X 10.9.3 (13D65)

I went to the App Store last night and saw the update and went ahead and let it download and reboot. Came back in 30 minutes and saw that I had the grey screen with the little box saying "updating" with 4 minutes remaining. Thought I would go to bed and let it do its thing overnight and I'd come back in the morning.

When I woke up this morning and looked, the screen was the SAME. The update bar hadn't progressed and it still said 4 minutes! I was horrified but I didn't just want to leave my computer sitting that way the whole day so I shut it down. Now I've probably completely horked my computer because I downloaded the $%R@$# update and now I have no computer. Thanks, Apple! 😝

Unbelievable, how can Apple do this to us?

Multi reboots in safe mode, zapped the PRAM, and a few more reboots and eventually it finished installing the update. It would seem that the update only gets half installed, I hate to speak too soon but it is now working okay.

My ill informmed suggestion is to just keep rebooting in safe mode and zapping the PRAM until something shifts.

The post near the top has all the information you need.

Good luck