openai/codex · error · anyhow::Error

{label} must be valid Unicode for remote MCP stdio

Error message

{label} must be valid Unicode for remote MCP stdio

What it means

Error "{label} must be valid Unicode for remote MCP stdio" thrown in openai/codex.

Source

Thrown at codex-rs/rmcp-client/src/stdio_server_launcher.rs:662

        }
        Ok(argv)
    }

    fn process_api_env(env: HashMap<OsString, OsString>) -> Result<HashMap<String, String>> {
        env.into_iter()
            .map(|(key, value)| {
                Ok((
                    Self::os_string_to_process_api_string(key, "environment variable name")?,
                    Self::os_string_to_process_api_string(value, "environment variable value")?,
                ))
            })
            .collect()
    }

    fn os_string_to_process_api_string(value: OsString, label: &str) -> Result<String> {
        value
            .into_string()
            .map_err(|_| anyhow!("{label} must be valid Unicode for remote MCP stdio"))
    }

    fn remote_env_policy(remote_env_vars: &[String]) -> ExecEnvPolicy {
        let include_only = if remote_env_vars.is_empty() {
            Vec::new()
        } else {
            // `source = "remote"` means the value is read from the executor's
            // environment, not copied from Codex. Start from `All` only so the
            // named remote variable is available to the filter below; the
            // effective child env is still limited by `include_only`.
            crate::utils::DEFAULT_ENV_VARS
                .iter()
                .map(|name| (*name).to_string())
                .chain(remote_env_vars.iter().cloned())
                .collect()
        };
        ExecEnvPolicy {
            inherit: if remote_env_vars.is_empty() {

View on GitHub (pinned to 339751715c)

When it happens

Trigger: Thrown at codex-rs/rmcp-client/src/stdio_server_launcher.rs:662 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of openai/codex@339751715c (2026-08-25). Data as JSON: /api/errors/acaf78800e02e6ba. Report an issue: GitHub.