OS X El Capitan installation error: AMD-Action:authenticate:SP When doing a clean re-installation of El Capitan (highest supported version) from a bootable USB on an older Mac (MBP, 15-inch, Late 2008), I get this error:

An unexpected error occured while signing in.
AMD-Action:authenticate:SP

The error shows up, while logging in with the Apple ID into the App Store in the installer.

I tried with different Apple IDs,

Also tried running these commands
in the Recovery Terminal and restarting:
csrutil clear
csrutil enable
The problem was that the old Mac did not have its date set correctly. 


Hold Option (ALT) + Command + R at Mac startup to start internet recovery
Going into Utilities &gt; Terminal starts the recovery terminal
Run date mmddHHMMyy - this solves the problem (date must be in PST!)
Run csrutil enable
Run csrutil clear
Exit the recovery terminal and continue OS X installation normally.


Here is the full step-by-step solution to solve the problem.