An error occurred while uploading the sketch
Yoooooooo! I just installed two units (UNO and a MEGA) on a Windows System. Although my Device Manager recognized the MEGA as "Arduino Mega 2560 (COM3)" At UPLOAD time I will get:
"avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_getsync(): timeout communicating with programmer
An error occurred while uploading the sketch"
The fix is simple: Under TOOLS/BOARD: select "Arduino/Genuino Uno" instead of the "Arduino/Genuino Mega" that you will be inclined to select cz.. that's what the device manager is stating you have!! 
Also, make sure u selected the PORT under TOOLS/PORT:
Now I am a happy dual Arduino board guru! XD
If it's still confusing just give me a shout and I'll gladly help 