I can't login to my MacBook after restarting to install OS X El Capitan, anyone else?

Please read this whole message before doing anything.

This procedure is a diagnostic test. It’s unlikely to solve your problem. Don’t be disappointed when you find that nothing has changed after you complete it.

The purpose of the test is to determine whether the problem is caused by third-party software that loads automatically at startup or login, by a peripheral device, by a font conflict, or by corruption of the file system or of certain system caches.

Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards, if applicable. Start up in safe mode and try to log in to the account with the problem.

Note: If FileVault is enabled in OS X 10.9 or earlier, or if a firmware password is set, or if the startup volume is a software RAID, you can’t do this. Ask for further instructions.

Safe mode is much slower to start up and run than normal, with limited graphics performance, and some things won’t work at all, including sound output and Wi-Fi on certain models. The next normal startup may also be somewhat slow.

The login screen appears even if you usually login automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.

Same problem?

After testing, restart as usual (not in safe mode) and verify that you still have the problem. Post the results of the test.

i use a MacBook Pro (Retina, Mid 2012) and i have similar issue,in my case i reinstalled the OS using Command +Shift+R it starts fine and works fine too but until i restart and the problem is back same stuck on apple logo or log screen if auto login is enabled which it was at first with file vault active,on my second reinstallation i turned off those and tried restarting it but no use the problem was there,i repeated that for like five times now but it doesn't fix and now that i am not restarting my PC is working I'm quite sure i'll have the problem if i restart ..new problem that i faced today is i couldn't even upgrade my iTunes to 12.3.1 from 12.3.0 App Store won't install it. If you have any solution or suggestion it would be nice.Thanks in Advance

I can't get mine started either. I have tried several times. Every time it says there is an error and I need to restart. I have a MacBook Pro and this problem has never occurred during system updates.

I have a mid-2012 Mac book Pro that once updated, randomly freezes, gives me a black screen and is completely unresponsive. The only chance I then have is to hold power button for 10 seconds and then restart. MAYBE, 10% of the time will it then actually boot up all the way. I have been through a few website's suggestions to no avail. I did the hardware test and that was fine. This is clearly an OS problem. I have checked for some sort of virus also, to no avail. I am frankly a ****** off, because the Yosimite update bricked an iMac I have at home as well. It is a 2008 computer that now won't even run.

And Oh ya, my MacBook Pro is about 3 months past the Apple Care expiration. Anybody have any ideas?

I have a similar issue. I was able to run the hardware test, which said it was normal. I cannot get my computer to load in the safe mode. It just does nothing. The only chance I have to get it to boot is to not touch any of the keys when I restart. Even then, it will boot somewhere between 5 and 10% of the time. Very frustrated