2011 MBP only boots in safe mode after yosemite update

Question

After attempting to update to yosemite, 2011 MBP (16GB Ram, 1TB HD) will only boot into safe mode. If I reboot without holding the shift key, I get the Apple logo and progress bar ......... that never goes away, just hangs about half way through. Any help?
Dan

Answer 1

Hey there Danielrbjo,
It sounds like you are unable to boot your mac without using Safe Boot. I would use the other troubleshooting from the following article, named:
Mac OS X: Gray screen appears during startup
Disconnect, test peripheral devices and network cables
Note: "Peripheral devices" refers to external devices other than what came with your Mac, such as hard drives, printers, or hubs that you connect via a USB or FireWire cable.
Shut down your Mac. If necessary, hold your Mac's power button for several seconds to force it to power down.
Disconnect all peripheral devices such as external hard drives or printers (leave only the display, a keyboard, and mouse connected).
Disconnect any Ethernet cables.
Start up your Mac.
If you can start up this way, one or more of your peripheral devices (or installed software related to the device) is probably causing the gray screen issue. Connect one device, then restart your Mac to test for the issue. Repeat the process until you locate the device at issue. Make sure the device is powered if it needs to be to operate correctly. Check with the manufacturer of the device for support or possible software driver or firmware updates that may be available for the device. Try a different cable with the device if possible (such as a different USB or FireWire cable). 
Note: If you have multiple peripheral devices and the issue only occurs when they are all connected, but not when each device is the only peripheral connected, see the Additional Information section below.
If you are using a desktop Mac with a third-party keyboard and/or mouse device, and the issue still occurs, try starting up with an Apple keyboard and mouse connected instead. Try starting with no keyboard and mouse connected, then connect them after start up. Also, try a different USB port on your Mac.
If the gray screen issue persists with no devices connected, go to the next section (with the peripherals still disconnected).
Reset the NVRAM / PRAM
Shut down your Mac. If necessary, hold your Mac's power button for several seconds to force it to power down.
Reset the NVRAM / PRAM.
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.
Shut down your Mac. If necessary, hold your Mac's power button for several seconds to force it to power down.
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.
Remove any third-party RAM that has been installed.
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.
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. 
Thank you for using Apple Support Communities.
All the best,
Sterling