MBP Early 2011 17" beeping when installing 10.11.4.

[SOLLERBOY]

Hi, I am just updating my machines to 10.11.4 and my MBP had downloaded the update and was installing, the progress bar was about half way and it went dead, a few seconds later there was a really long single beep that I've never heard before.

After that it tried booting several times with the normal bong but kept restarting itself at the apple logo. It did this about 6 times and then returned to the normal installation screen.

It has just finished and seems to be working ok, does anyone know what the beeping means?

 

[priitv8]

Not sure if this is what you heard, but this is supposed to be the official explanation:
https://support.apple.com/en-us/HT202768

 

[MacInTO]

I heard it on all four of my MBPs and all went well.