Struct MethodNotFoundError 

pub struct MethodNotFoundError {
    pub code: i64,
    pub data: Option<Value>,
    pub message: String,
}

Latest MCP Protocol 2026_07_28 A JSON-RPC error indicating that the requested method does not exist or is not available. In MCP, a server returns this error when a client invokes a method the server does not implement — either a genuinely unknown method, or one gated behind a server capability the server did not advertise (e.g., calling prompts/list when the prompts capability was not advertised). A request that requires a client capability the client did not declare is signalled instead by {@link MissingRequiredClientCapabilityError} (-32021).

JSON schema

{
 "description": "A JSON-RPC error indicating that the requested method does not exist or is not available.\n\nIn MCP, a server returns this error when a client invokes a method the server does not implement — either a genuinely unknown method, or one gated behind a server capability the server did not advertise (e.g., calling prompts/list when the prompts capability was not advertised).\n\nA request that requires a client capability the client did not declare is signalled instead by {@link MissingRequiredClientCapabilityError} (-32021).",
 "type": "object",
 "required": [
   "code",
   "message"
 ],
 "properties": {
   "code": {
     "description": "The error type that occurred.",
     "type": "integer",
     "const": -32601
   },
   "data": {
     "description": "Additional information about the error. The value of this member is defined by the sender (e.g. detailed error information, nested errors etc.)."
   },
   "message": {
     "description": "A short description of the error. The message SHOULD be limited to a concise single sentence.",
     "type": "string"
   }
 }
}

Fields

code: i64

The error type that occurred.

data: Option<Value>

Additional information about the error. The value of this member is defined by the sender (e.g. detailed error information, nested errors etc.).

message: String

A short description of the error. The message SHOULD be limited to a concise single sentence.

Trait Implementations

impl Clone for MethodNotFoundError

fn clone(&self) -> MethodNotFoundError

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for MethodNotFoundError

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for MethodNotFoundError

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for MethodNotFoundError

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.