Q: Yosemite Upgrade - iMac mid-2011 - Stuck on white progress bar screen at about 50%

SATopWater - totally worked!   Thank you!

Thank you so much!  I waited and waited... I slept... I ate... I played with my son... 24hrs later, still stuck at 50% on that progresss bar.  Tried this and now I'm using Yosemite!  Lesson learned... wait a few weeks before installing a new operating system.  Thanks!

This worked for me!  Thank you.

Thank you thank you thank you.  This fix saved my system!!

APPLE, take note!

I had this exact same problem, and was panicking as it was on my work Macbook Pro. SATopWater's solution worked perfectly!

I suppose the developers didn't take into consideration, that when the upgrade process walks the bus and hits the WLAN adapter, they should have written a timeout function to prompt the user to, either abort or ignore.

Thanks, Sparkleberry, the shift key worked for me on my iMac.  Had tried option, etc and nothing worked.  Use the Shift key after power of and the screen came up that the install was completing.  Once it completed, it restarted and was running new OS.

WWorked,for me too. Thanks a million times.

You are a genius. Thank you so much. I was panicking as this my main computer used for both work and home. Cheers

Hi,

I hope to say that this will fix my problem as well. I just did all steps, but I wanted to ask,  how long do you believe it will take to reboot the system after the last step? I should just wait to see what happen?

Thanks

Oscar

Thanks!

I followed the guide from SATopWater at first and after rebooting it got stuck at 50% again. So then I tried the Shift method from bazapple and that seemed to work. However, I wanted to mention that i also tried logging in to a different account than I did the first times. In case your Mac has multiple accounts you may try logging into a (smaller?) user account.

HHubiera,

whtat is the shift method? 

updated of my situation: it was 50% and the monitor turns black. It sounds that the computer is still running but I don't know what to do next. Any suggestions?

The shift method

Power down the machine

Power the machine on

Immediately hold down the SHIFT key, but do so after the start up chime but before the Apple logo appears

From there, you're in a sort of maintenance mode with some system utilities available.  For me, simply turning off the WiFi (icon in top right bar), and then selecting "Restart" from the menu.

Once my machine restarted, everything was working with the new upgrade.

--A

Just how long does it take to download Yosemite?  In the app store window, it shows that it's has been downloading for a long time, but there is no indication anywhere that it is actually downloading.

When I try to reboot holding command r the screen just goes all gray and unresponsive, am I doing something wrong? Thanks