This error usually means that you are trying to declare a function or class that has already been declared in your script.

How can i fix it

Do not declare things twice, like functions, classes, etc...

//----------------------------------------
// Let us say you have this function
//----------------------------------------
function sayHi(){ 
    echo "hi";
}
// That same function cannot be redeclared
function sayHi(){ 
    echo "Goodbye";
}
//----------------------------------------
// Same goes for classes
//----------------------------------------
class sayHi{}
// Do not declare any class twice
class sayHi{}