I have a Macbook Pro Medio 2012, 15 Inch Non Retina. It was running on a normal 750G HDD, but i wanted an upgrade, so i bought the Samsung V-Nand 850 EVO SSD 1TB.

I created a Bootable El-Capitan USB Stick, so i could do a clean install. After i swapped the HDD with the Samsung SSD, i plugged in my Bootable USB stick and turned on my macbook.

First it shows the apple logo with a loading line. after that i gives me a "stop sign". A circle with a line running through it.

I also tried pressing the Command button while it starts up, but that didn't work.

I'm trying to clean install El Capitan on my Macbook pro.

Does anyone know what to do?

Kind regards in advance!

1 Answer 1


I found the ususal 8GB USB drive was not large enough and only got El Capitan to boot from USB of 16GB or more!

You can see what is happening when you boot the mac using Verbose mode like so:

Right upon hearing the startup chime, press and hold the Command (⌘) – V key combination for Verbose Mode.

As the Mac boots it will spit out lines of code:

You may be able to see whta the problem is from this, or come back and type in teh last few lines fro us to read. Or take a pic with your phone and post that!

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