{"id":1198,"hash":"f71d125abe03ab5d51523bcefb2db72916b07f5256825d5657c606d425761900","pattern":"the trait `std::convert::From&lt;mongodb::error::Error&gt;` is not implemented for `std::io::Error`","full_message":"Trying to make server with actix-web & mongodb in rust.  Getting error \n\n  the trait std::convert::From<mongodb::error::Error> is not implemented for std::io::Error\n\nhere is my code\n\nuse actix_web::{web, App, HttpRequest, HttpServer, Responder};\nuse mongodb::{options::ClientOptions, Client};\n\nasync fn greet(req: HttpRequest) -> impl Responder {\n    let name = req.match_info().get(\"name\").unwrap_or(\"World\");\n    format!(\"Hello {}!\", &name)\n}\n\n#[actix_rt::main]\nasync fn main() -> std::io::Result<()> {\n    // Parse a connection string into an options struct.\n    let mut client_options = ClientOptions::parse(\"mongodb://localhost:27017\")?;\n\n    // Manually set an option.\n    client_options.app_name = Some(\"My App\".to_string());\n\n    // Get a handle to the deployment.\n    let client = Client::with_options(client_options)?;\n\n    // List the names of the databases in that deployment.\n    for db_name in client.list_database_names(None)? {\n        println!(\"{}\", db_name);\n    }\n\n    HttpServer::new(|| {\n        App::new()\n            .route(\"/\", web::get().to(greet))\n            .route(\"/{name}\", web::get().to(greet))\n    })\n    .bind(\"127.0.0.1:8000\")?\n    .run()\n    .await\n}\n\nDid I missed anything?","ecosystem":"cargo","package_name":"mongodb","package_version":null,"solution":"Reasoning\n\nIt means that one of the functions you are calling with a ? at the end can return a mongodb::error::Error. But the signature of the main is a std::io::Result<()>, which is an implied Result<(), std::io::Error>. The only error type it can accept is an io::Error, not a mongodb::Error.\n\nIt looks like all the functions you are escaping might return this mongodb::error::Error, so you can try to change the main signature to such a result: Result<(). mongodb::error::Error>.\nBut I would recommend you do proper error handling on those potential errors, as this is your main().\n\nSolution\n\nChange those ? to .expect(\"Some error message\"); at least. The program will still crash, but it will crash in a way that is meaningful to you.","confidence":0.85,"source":"stackoverflow","source_url":"https://stackoverflow.com/questions/61472244/the-trait-stdconvertfrommongodberrorerror-is-not-implemented-for-st","votes":4,"created_at":"2026-04-19T04:52:34.058051+00:00","updated_at":"2026-04-19T04:52:34.058051+00:00"}