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

This worked... https://www.afp548.com/2015/01/14/when-yosemite-has-fallen-and-it-cant-get-up/

I followed the instructions you suggested, exactly as you said and the problem was solved thanks very much.

However from what i observed its almost like Yosmite is being completely installed but the computer just doesnt restart on its own you had to do it manyually. And its stuck with the 50% progress bar untill you do the restart yourself. I wonder if its cuz your computer fell asleep during update, that something like that happens or something?

My model is the 2010 macbook pro.

THANK YOU.  That worked perfectly.  I also had the same iMac, and tried to reinstall from the recovery partition, but it ALSO got stuck at 50%.  I left it overnight, but it was still stuck.

So tried your tip and it rebooted successfully into the new OS. 

I can relax now!

Thanks, it worked for iMac 2009

Wow, I can't believe this.  I was trying to open a Pages file on my iMac that I had emailed from my Macbook Air.  It told me I had to upgrade my Pages app. So I tried to do that and it said in order to upgrade Pages I needed to install 10.10.1 OS X.   So I did that.  And my iMac crashed like all of yours.  I called Apple Care and they said my disk was bad so I had to reformat my Hard Drive and lose everything.  My Time Machine backup unfortunately was from like 3 years ago.  I lost thousands of pictures.  I was able to recover most of them (I hope) through a $120 Hard Drive recovery program I found. 

Then today I tried to use Pages again.  Same thing.  So I think to myself no problem, I'll just upgrade to Yosemite now because I reformatted my HD so my computer is fixed now. 

Now I'm going through the same thing again.  I can't believe this.

It was stuck at 50% for hours and hours.  I tried Command R about 5 times on boot up.  Didn't work.  I tried Shift about 10 times.   Didn't work.  It just goes to the Apple loading screen every time.  I've tried clicking it and holding it and letting it go at different times.  Is this the wireless keyboard problem.

Please help me!

Update:

I finally got the Command R to work and I turned off Wi-Fi and restarted but this didn't help.  Went straight back to the 50% loading screen.  I have tried the SHIFT start for Safe Mode but it never works.

I am at a loss.  I have lost so many hours of my life and work trying to fix this thing, not to mention how many files I lost because Apple told me to reformat my HD. 

I never thought anything like this could come from Apple. 

I have no idea what to do now.

Billfromcanton - I don't know for certain that this helps, but it IS part of the process I've seen documented in various places on the web.

Boot into the recovery disk.  Run disk utility and REPAIR PERMISSIONS on your regular drive.  Then try the install again from the recovery partition.   I think this helped me, but then I still got stuck and had to do the wifi dance thing noted above which DID work (from SATopWater in this thread)

You need to use command-R to get into recovery mode and access disk utility from there.  This is NOT the same as safe mode.

http://www.tekrevue.com/tip/mac-startup-options/

Hope this helps!

Thanks Big Daddy,

As you were responding I got into disk utility and repaired drive and then started install of Yosemite and this time it worked!  Thanks so much.  I can't believe what an ordeal it was.  Thanks again to everyone.

I'm trying to boot in S Mode. I still have that b***y progress bar stuck before 50 %.

I already tried repair disk (it had nothing wrong) and repair permissions in Dik Utility under Mode Recovery.

Still got that bloody bar stuck !

This solved my question by SATopWater on Oct 17, 2014 12:41 PM

I'm not recommending this to anyone, just thought I'd report on what worked for me:

-  Let Yosemite upgrade sit at the white progress bar screen at 50% for 4 hours.

-  Once I was nearly positive it wasn't doing anything like writing to the hard drive...

-  Held power button for 10 seconds to turn computer off

-  Waited about 10 seconds again

-  Turned power on and held Command R  (It took about 3 minutes to boot)

-  Clicked on WI-Fi symbol on upper right and turned off Wi-Fi

-  Selected restart from the System menu option

-  Computer rebooted and finished the upgrade

I have since rebooted (twice to be sure) and run a few things and all seems fine at this point.

This worked for me too!

See the answer in context

This worked for me too, Macbook Pro mid 2012. Seriously why doesn't the upgrade come with an alert message to save us all from complete panic? Simply getting the wifi connection off as above did the trick for me.  So grateful for SATopWater sharing in October but wondering why this is still an issue four months later!?

Worked for me too on a 2009 MacBook...like Magic...Thank you!!!!

ok.

I have an older mac book pro.  2006-2009?

I held power key and counted to 10.  Powered off.  Counted to 10 than held shift key down and pushed power while still olding shift key down. 4 minutes or so later I let shift key up . Machine opened in safe mode.  The machine was sluggish at best.   Powered off again and waited one minute.  Restarted in regular fashion with the power key only.  Seems to be working well. 

THANK YOUUUUUUU!!!!!! 

So I waited over 24 hours with the upgrade at about 50%.  The shut down and reboot using the Command + R, turn off wifi, and reboot worked for me.  After it restarted it took very little time to get to the login screen and the Yosemite upgrade appears to be complete. 

Thanks!