Error shown while trying to update the BIOS from F.20 to F.21

Hello,
I took one more look at the Event Viewer and scrolled down because I wanted to know from where the error message was created.
Also, when I tried to update the BIOS from F.20 to F.21, the event 5 and event 4 showed ever since I set up this BIOS update.
Error : Event 13, ACPI
The embedded controller (EC) did not respond within the specified timeout period. This may indicate that there is an error in the EC hardware or firmware or that the BIOS is accessing the EC incorrectly. You should check with your computer manufacture for an upgraded BIOS. In some situation, this error may cause the computer to function incorrectly.

What is the reason? Please help me.
Thanks a lot.
