OS Error 5 when Writing to file on windows 10

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3

This is just example code but I got the same result nethertheless.

use std::io::Write;

fn main() {
    let mut file = std::fs::File::open("thing.txt").unwrap();
    file.write_all(b"PLACEHOLDER").expect("Something went wrong opening the file");
}

Result:

thread 'main' panicked at 'Something went wrong opening the file: Os { code: 5, kind: PermissionDenied, message: "Access is denied." }'