avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x41

While uploading my program into Adruino Uno board I am facing this problem. please help me out. I am working in Windows 7 64-bit. Port: COM8.
The program is for smart light control. The program is as follows:

/*

*/
String inputs;
#define relay1 2 //Connect relay1 to pin 9
#define relay2 3 //Connect relay2 to pin 8
#define relay3 4 //Connect relay3 to pin 7
#define relay4 5 //Connect relay4 to pin 6
#define relay5 6 //Connect relay5 to pin 5
#define relay6 7 //Connect relay6 to pin 4
#define relay7 8 //Connect relay7 to pin 3
#define relay8 9 //Connect relay8 to pin 2
void setup()
{
Serial.begin(9600); //Set rate for communicating with phone
pinMode(relay1, OUTPUT); //Set relay1 as an output
pinMode(relay2, OUTPUT); //Set relay2 as an output
pinMode(relay3, OUTPUT); //Set relay1 as an output
pinMode(relay4, OUTPUT); //Set relay2 as an output
pinMode(relay5, OUTPUT); //Set relay1 as an output
pinMode(relay6, OUTPUT); //Set relay2 as an output
pinMode(relay7, OUTPUT); //Set relay1 as an output
pinMode(relay8, OUTPUT); //Set relay2 as an output
digitalWrite(relay1, LOW); //Switch relay1 off
digitalWrite(relay2, LOW); //Swtich relay2 off
digitalWrite(relay3, LOW); //Switch relay1 off
digitalWrite(relay4, LOW); //Swtich relay2 off
digitalWrite(relay5, LOW); //Switch relay1 off
digitalWrite(relay6, LOW); //Swtich relay2 off
digitalWrite(relay7, LOW); //Switch relay1 off
digitalWrite(relay8, LOW); //Swtich relay2 off
}
void loop()
{
while(Serial.available()) //Check if there are available bytes to read
{
delay(10); //Delay to make it stable
char c = Serial.read(); //Conduct a serial read
if (c == '#'){
break; //Stop the loop once # is detected after a word
}
inputs += c; //Means inputs = inputs + c
}
if (inputs.length() >0)
{
Serial.println(inputs);

if(inputs == "A")
{
digitalWrite(relay1, LOW);
}
else if(inputs == "a")
{
digitalWrite(relay1, HIGH);
}
else if(inputs == "B")
{
digitalWrite(relay2, LOW);
}
else if(inputs == "b")
{
digitalWrite(relay2, HIGH);
}
else if(inputs == "C")
{
digitalWrite(relay3, LOW);
}
else if(inputs == "c")
{
digitalWrite(relay3, HIGH);
}
else if(inputs == "D")
{
digitalWrite(relay4, LOW);
}
else if(inputs == "d")
{
digitalWrite(relay4, HIGH);
}
else if(inputs == "E")
{
digitalWrite(relay5, LOW);
}
else if(inputs == "e")
{
digitalWrite(relay5, HIGH);
}
else if(inputs == "F")
{
digitalWrite(relay6, LOW);
}
else if(inputs == "f")
{
digitalWrite(relay6, HIGH);
}
else if(inputs == "G")
{
digitalWrite(relay7, LOW);
}
else if(inputs == "g")
{
digitalWrite(relay7, HIGH);
}
else if(inputs == "H")
{
digitalWrite(relay8, LOW);
}
else if(inputs == "h")
{
digitalWrite(relay8, HIGH);
}
inputs="";
}
}

I am not sure why you are posting your code.

Your problem is uploading on COM8.
Whether you Arduino is on COM8 is the question.

How can I confirm it?
Although I have verify it from device manager.

Swaroop_Mallick:
How can I confirm it?
Although I have verify it from device manager.

Confirm what?

Either your Arduino Uno shows up in Windows Device Manager at COM8 or it doesn’t.
If it doesn’t, then you probably need drivers
If it does, you may need a USB cable that is capable of data.

.