BoundaryML/baml · error

object method function returned nil pointer

Error message

object method function returned nil pointer

What it means

This error means the FFI call returned a buffer whose pointer is nil (even though its length was non-zero), i.e. the object method invocation returned no valid response pointer. This is an FFI contract violation indicating a native-side failure to allocate/return a response.

Solutions

1. Check FFI logs for the object type and pointer involved
2. Retry; if consistent, downgrade/upgrade BAML versions together
3. Reduce payload/argument sizes if near memory limits
4. Report to BAML maintainers with the FFI log

res, err := CallMethod(obj, m, kwargs)
if err != nil && strings.Contains(err.Error(), "returned nil pointer") {
    res, err = CallMethod(obj, m, kwargs) // one retry for transient native allocation failure
}

When it happens

Trigger: CallMethod (used by destructor, Type, ListProperties, AddProperty, Property, SetType) hitting a native response with nil buffer pointer; typically follows native memory allocation failure or misuse of the C wrapper.

Common situations: Out-of-memory in the native runtime; corrupted runtime handle; a bug in the C wrapper for a specific object type.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• failed to call object method function
• decodeLiteralValue: valueLiteral is nil
• destructor returned unexpected result
• encoding client registry
• encoding collector

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/392fa4199974891c. Report an issue: GitHub.

Appendix: source

Thrown at engine/language_client_go/baml_go/raw_objects/utils.go:182

		Object:     EncodeRawObject(object),
		MethodName: method_name,
	}

	encodedArgs, err := proto.Marshal(&args)
	if err != nil {
		return nil, fmt.Errorf("failed to marshal object method arguments: %w", err)
	}
	cEncodedArgs := (*C.char)(unsafe.Pointer(&encodedArgs[0]))

	cBuf := C.WrapCallObjectMethodFunction(object.Runtime(), cEncodedArgs, C.uintptr_t(len(encodedArgs)))

	content_bytes := C.GoBytes(unsafe.Pointer(cBuf.ptr), C.int32_t(cBuf.len))
	C.WrapFreeBuffer(cBuf) // Free the buffer after use
	if cBuf.len == 0 {
		return nil, fmt.Errorf("failed to call object method function")
	}
	if cBuf.ptr == nil {
		return nil, fmt.Errorf("object method function returned nil pointer")
	}

	var content_holder cffi.InvocationResponse
	err = proto.Unmarshal(content_bytes, &content_holder)
	if err != nil {
		return nil, fmt.Errorf("failed to unmarshal content bytes: %w", err)
	}

	parsed, err := decodeObjectResponse(object.Runtime(), &content_holder)
	if err != nil {
		return nil, fmt.Errorf("failed to decode object response: %w", err)
	}

	return parsed, nil
}

type nilObject struct {
	any

View on GitHub (pinned to bd85ce9dee)