Actix project: Os code: 9, Bad file descriptor

I doing a learning project with actix and a local json database so this whole project may seem a bit strange but my problem is that I'm getting this error message:
thread 'actix-rt:worker:0' panicked at 'what the heck: Os { code: 9, kind: Other, message: "Bad file descriptor" }'
I don't understand why.

I have an endpoint "localhost.../signup" that is calling "post_signup" handler function.
The panic occurs in the function "update_user_index" when I'm trying to write to the file and I just don't get it.
File exists, filename and path is correct.

If I missed any relevant info, let me know.

pub async fn post_signup(body: web::Json<User>) -> Result<HttpResponse> {
    match get_user_by_email(body.clone().email) {
        Some(body) => Ok(HttpResponse::Unauthorized().json(LoginResponse {
            message: format!("User '{}' already exists, sign in instead.",,
        None => {
            let new_user = add_new_user(&body)?;
                    http::Cookie::build("jwt", "j903jfdsfff")
                        .max_age(60 * 60 * 24 * 7 * 4 * 3)
                .json(LoginResponse {
                    message: format!("{}, logged in.",,
pub fn get_user_index() -> Result<UserIndex> {
    let mut file = File::open("./database/index_users.json")?;
    let mut data = String::new();
    file.read_to_string(&mut data)?;

pub fn update_user_index(new_user: Index) -> Result<()> {
    let mut users: UserIndex = get_user_index()?;
    println!("{:?}", &users);
    let mut file = File::open("./database/index_users.json")?;
    write!(file, "{}", serde_json::to_string(&users)?).expect("what the heck");
pub fn get_user_file(id: String) -> Result<User> {
    let mut file = File::open(format!("./database/users/{}.json", id))?;
    let mut data = String::new();
    file.read_to_string(&mut data)?;
  1. File::open will open the file in read only mode.
  2. Since you are using actix, an async library based on tokio - you should open files using tokio's API too.

Oh.. now I feel silly, could probably have figured that out.
Thanks for the quick and helpful respone :slight_smile: !

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.