Holochain Forum

Problem connecting to a running conductor (app id not found)

I’m new to Holochain and started with the tutorials recommended in the Developer section:

Everything worked out as described and the conductor was up and running the hApp

$ hc sandbox call 1 list-apps
hc-sandbox: List Apps: [InstalledAppInfo { installed_app_id: "test-app", cell_data: [InstalledCell { cell_id: CellId(DnaHash(uhC0kUIew8M-K2ZAUmh1NywzP4Emo050Zmp5oaldzSf2aGsq09SFp), AgentPubKey(uhCAkomVJo2MHkqqSPmovoQOSvOztAMrGqfKmHyd7lsbPGg_ZuTgF)), cell_nick: "sample-slot" }], status: Running }]

Then I went through this tutorial to connect to my hApp:

I used the Rust example code:

use hdk::prelude::{
    holochain_zome_types::zome::{FunctionName, ZomeName},
    ExternIO, SerializedBytes,
use holochain_conductor_api::ZomeCall;
use holochain_conductor_api_rust::AppWebsocket;
use serde::*;

const WS_URL: &str = "ws://localhost:8888";
const H_APP_ID: &str = "test-app";
const ZOME_NAME: &str = "numbers";
const FN_NAME: &str = "add_ten";

// custom data we want to pass the hApp
#[derive(Serialize, Deserialize, SerializedBytes, Debug, Clone)]
struct ZomeInput {
    number: i32,

// custom data we want back from the hApp
#[derive(Serialize, Deserialize, SerializedBytes, Debug, Clone)]
pub struct ZomeOutput {
    other_number: i32,

pub async fn call() -> Result<ZomeOutput, String> {
    // connect to a running holochain conductor
    // (there needs to be a running holochain conductor!)
    let mut app_ws = AppWebsocket::connect(WS_URL.to_string())
        .or(Err(String::from("Could not connect to conductor")))?;
    let app_info_result = app_ws
        .or(Err(String::from("Could not get app info")))?;
    let app_info = match app_info_result {
        None => return Err(String::from("no app info found")),
        Some(app_info) => app_info,
    let cell_id = app_info.cell_data[0].as_id().to_owned();

    let payload = ZomeInput { number: 10 };
    // you must encode the payload to standardize it
    // for passing to your hApp
    let encoded_payload = ExternIO::encode(payload.clone())
        .or(Err(String::from("serialization of payload failed")))?;

    // define the context of the request
    let api_request = ZomeCall {
        cell_id: cell_id.clone(),
        zome_name: ZomeName::from(String::from(ZOME_NAME)),
        fn_name: FunctionName::from(String::from(FN_NAME)),
        payload: encoded_payload,
        cap: None,
        provenance: cell_id.clone().agent_pubkey().to_owned(),

    // make the request
    let encoded_api_response = app_ws
        .map_err(|e| {
            println!("{:?}", e);
        .or(Err(String::from("zome call failed")))?;

    // you must decode the payload from
    // the standarized format its returned as
    let result: ZomeOutput = encoded_api_response
        .or(Err(String::from("deserialization failed")))?;


async fn main() {
    match call().await {
        Ok(s) => println!("Result of the call: {:#?}", s),
        Err(e) => println!("Got an error: {:?}", e),

Compiling and running gave this error:

$ cargo run
   Compiling happ-client-call-tutorial v0.1.0 (/home/stefan/dev/rust/holochain/happ-client-call-tutorial)
   Finished dev [unoptimized + debuginfo] target(s) in 22.85s
   Running target/debug/happ-client-call-tutorial
Got an error: "Could not get app info"

The conductor says it’s running app with id “test-app” and the example is trying to connect to H_APP_ID = “test-app”,

My questions here:
Why does the connection fail?
How can one debug such a situation?

Thanks in advance,

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