Steve,
Pointing out the line that says "Failed to validate the serial number" does not help the customer with his problem. We know the validation failed; that goes with code 14. What the customer needs is help finding WHY it failed. Also, I need the same.
In my own case, I have checked network connectivity and can reach adobe servers.
I'm using a serial number retrieved from a redemption code for Acrobat DC (12). I have entered the serial number with no spaces, with spaces, and with hyphens instead of spaces. Now, pay attention to this:
I HAVE HAD A CO-WORKER CHECK MY TYPING TO ENSURE THAT I ENTERED THE SERIAL CODE CORRECTLY.
Also, we are working from a printout of the serial code as provided by Adobe, NOT manually copied from the screen.
Several lines above the "Failed" line, the error log (running on a separate machine or I'd copy/paste it) says that this is an "OOBELib Bad Serial Number." Given that this serial is a printout from Adobe and HAS BEEN TYPED CORRECTLY, then that's IMPOSSIBLE.
What is going on??