E0030: Wrong Number of Arguments

You called a function with the wrong number of arguments.

Example

fn add(a: i64, b: i64) -> i64 {
    a + b
}

fn main() {
    add(1);        // Error: function expects 2 arguments but 1 was provided
    add(1, 2, 3);  // Error: function expects 2 arguments but 3 were provided
}

How to fix

Pass the correct number of arguments:

fn add(a: i64, b: i64) -> i64 {
    a + b
}

fn main() {
    add(1, 2);  // OK
}