grpc/grpc-go · error

extproc: failed to unmarshal config

Error message

extproc: failed to unmarshal config %v: %v

What it means

Returned by ParseFilterConfig when anypb.Any.UnmarshalTo fails to decode the packed bytes into an ExternalProcessor message. Usually the type_url does not match ExternalProcessor's full name, the bytes are corrupted, or the proto schema versions between control plane and client are incompatible. Hit at ext_proc.go:115.

Solutions

1. Verify the Any.type_url matches the builder's advertised TypeURL (see TypeURLs() in ext_proc.go:86).
2. Align the go-control-plane version between the control plane and grpc-go client.
3. Re-serialize the resource from a known-good ExternalProcessor message.
4. Check the server logs / xDS dump (e.g. via xds-resolver debugging) for the raw bytes and validate them standalone.

Example fix

// control plane - before
any, _ := anypb.New(otherFilterMsg)
// after: ensure correct type and version
any, _ := anypb.New(&v3extproc.ExternalProcessor{...})
// confirm any.TypeUrl == "type.googleapis.com/envoy.extensions.filters.http.ext_proc.v3.ExternalProcessor"

// verify type URL and decodability before sending
want := "type.googleapis.com/envoy.extensions.filters.http.ext_proc.v3.ExternalProcessor"
if any.TypeUrl != want { return fmt.Errorf("wrong type_url %q", any.TypeUrl) }
probe := new(v3extproc.ExternalProcessor)
if err := any.UnmarshalTo(probe); err != nil { return err }

When it happens

Trigger: The xDS resource delivers an *anypb.Any whose type_url is not type.googleapis.com/envoy.extensions.filters.http.ext_proc.v3.ExternalProcessor, or whose value bytes are malformed / from a newer proto revision with unknown fields that UnmarshalTo rejects.

Common situations: Control plane and grpc-go use different versions of go-control-plane with incompatible ext_proc protos; type URL typo in the control plane; resource corrupted in transit or by a buggy serializer; wrong filter is wired to the ext_proc type URL.

Related errors

• extproc: failed to unmarshal override
• external processor sent an immediate response but immediate…
• extproc: empty grpc_service provided in config
• extproc: error parsing config
• extproc: error parsing override

AI-assisted analysis of grpc/grpc-go@0c51461d27 (2026-08-11). Data as JSON: /api/errors/b7495d130a375bc2. Report an issue: GitHub.

Appendix: source

Thrown at internal/xds/httpfilter/extproc/ext_proc.go:116

		return fmt.Errorf("extproc: invalid request body mode %v: want %q or %q", m, "NONE", "GRPC")
	}
	if m := mode.GetResponseBodyMode(); m != v3procfilterpb.ProcessingMode_NONE && m != v3procfilterpb.ProcessingMode_GRPC {
		return fmt.Errorf("extproc: invalid response body mode %v: want %q or %q", m, "NONE", "GRPC")
	}
	if mode.GetResponseBodyMode() == v3procfilterpb.ProcessingMode_GRPC && mode.GetResponseTrailerMode() != v3procfilterpb.ProcessingMode_SEND {
		return fmt.Errorf("extproc: invalid response trailer mode %v: must be %q when response body mode is %q", mode.GetResponseTrailerMode(), "SEND", "GRPC")
	}
	return nil
}

func (builder) ParseFilterConfig(cfg proto.Message) (httpfilter.FilterConfig, error) {
	m, ok := cfg.(*anypb.Any)
	if !ok {
		return nil, fmt.Errorf("extproc: error parsing config %v: unknown type %T, want *anypb.Any", cfg, cfg)
	}
	msg := new(v3procfilterpb.ExternalProcessor)
	if err := m.UnmarshalTo(msg); err != nil {
		return nil, fmt.Errorf("extproc: failed to unmarshal config %v: %v", cfg, err)
	}
	if msg.GetProcessingMode() == nil {
		return nil, fmt.Errorf("extproc: missing processing_mode in config %v", cfg)
	}
	if err := validateBodyProcessingMode(msg.GetProcessingMode()); err != nil {
		return nil, err
	}

	if msg.GetGrpcService() == nil {
		return nil, fmt.Errorf("extproc: empty grpc_service provided in config %v", cfg)
	}
	server, err := iextproc.ParseGRPCServiceConfig(msg.GetGrpcService())
	if err != nil {
		return nil, fmt.Errorf("extproc: failed to parse grpc_service %v", err)
	}

	mutationRules, err := httpfilter.HeaderMutationRulesFromProto(msg.GetMutationRules())
	if err != nil {

View on GitHub (pinned to 0c51461d27)