Enum HandlerError 

#[non_exhaustive]
pub enum HandlerError {
    UserCancelled,
    Timeout {
        timeout_seconds: u64,
    },
    InvalidInput {
        details: String,
    },
    Configuration {
        message: String,
    },
    Generic {
        message: String,
    },
    External {
        source: Box<dyn Error + Send + Sync>,
    },
}

Errors that can occur during handler operations

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

UserCancelled

Handler operation failed due to user cancellation

Timeout

Handler operation timed out

Fields

timeout_seconds: u64

InvalidInput

Input validation failed

Fields

details: String

Configuration

Handler configuration error

Fields

message: String

Generic

Generic handler error

Fields

message: String

External

External system error (e.g., UI framework, database)

Fields

source: Box<dyn Error + Send + Sync>

Implementations

impl HandlerError

pub fn into_jsonrpc_error(&self) -> JsonRpcError

Convert handler error to JSON-RPC error

This method centralizes the mapping between handler errors and JSON-RPC error codes, ensuring consistency across all handlers.

Error Code Mapping

• -1: User rejected sampling request (MCP 2025-06-18 spec)
• -32801: Handler operation timed out
• -32602: Invalid input (bad request)
• -32601: Handler configuration error (method not found)
• -32603: Generic/external handler error (internal error)

Examples

use turbomcp_client::handlers::HandlerError;

let error = HandlerError::UserCancelled;
let jsonrpc_error = error.into_jsonrpc_error();
assert_eq!(jsonrpc_error.code, -1);
assert!(jsonrpc_error.message.contains("User rejected"));

Trait Implementations

impl Debug for HandlerError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for HandlerError

fn fmt(&self, __formatter: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Error for HandlerError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl From<Box<dyn Error + Sync + Send>> for HandlerError

fn from(source: Box<dyn Error + Send + Sync>) -> Self

Converts to this type from the input type.