grpc/grpc-go · error

extproc: invalid request body mode

Error message

extproc: invalid request body mode %v: want %q or %q

What it means

Returned by validateBodyProcessingMode when ProcessingMode.request_body_mode is neither NONE nor GRPC. grpc-go's ext_proc client only supports NONE (do not send body) and GRPC (buffer whole gRPC messages); Envoy's STREAMED and BUFFERED modes are intentionally unsupported. Hit at ext_proc.go:97.

Solutions

1. Set processing_mode.request_body_mode to NONE or GRPC in the xDS config.
2. If you need streaming body processing, run Envoy as the data plane instead of grpc-go's built-in ext_proc.
3. Confirm the grpc-go version supports ext_proc at all (gated by GRPC_XDS_EXTPROC env var / envconfig.XDSClientExtProcEnabled).
4. Audit the control-plane template that emits processing_mode for hard-coded STREAMED/BUFFERED.

Example fix

# xDS config - before
processing_mode:
  request_body_mode: STREAMED
# after
processing_mode:
  request_body_mode: GRPC

// control-plane / config-author guard
allowed := map[int32]bool{0: true /*NONE*/, 2: true /*GRPC*/}
if !allowed[int32(cfg.ProcessingMode.RequestBodyMode.Number())] {
  return fmt.Errorf("request_body_mode must be NONE or GRPC")
}

When it happens

Trigger: An xDS ExternalProcessor config is applied whose processing_mode.request_body_mode is STREAMED or BUFFERED. ParseFilterConfig (or ParseFilterConfigOverride) calls validateBodyProcessingMode, which returns this error, and the resource is rejected.

Common situations: An Envoy-targeted config is reused verbatim against a grpc-go client; a control plane emits STREAMED by default; an operator switches body mode expecting streaming mutation support that grpc-go does not implement.

Related errors

• extproc: invalid response body mode
• extproc: invalid response trailer mode
• external processor sent an immediate response but immediate…
• external processor unexpectedly sent request body when…
• external processor unexpectedly sent response body when…

AI-assisted analysis of grpc/grpc-go@0c51461d27 (2026-08-11). Data as JSON: /api/errors/15acff9d51dc3e4d. Report an issue: GitHub.

Appendix: source

Thrown at internal/xds/httpfilter/extproc/ext_proc.go:98

func timeSince(t time.Time) time.Duration {
	return iextproc.TimeSinceFunc(t)
}

type builder struct{}

func (builder) TypeURLs() []string {
	return []string{
		"type.googleapis.com/envoy.extensions.filters.http.ext_proc.v3.ExternalProcessor",
		"type.googleapis.com/envoy.extensions.filters.http.ext_proc.v3.ExtProcPerRoute",
	}
}

// validateBodyProcessingMode ensures that the body processing mode is either
// NONE or GRPC. Also ensures that if response body mode is GRPC then response
// trailer mode must be SEND.
func validateBodyProcessingMode(mode *v3procfilterpb.ProcessingMode) error {
	if m := mode.GetRequestBodyMode(); m != v3procfilterpb.ProcessingMode_NONE && m != v3procfilterpb.ProcessingMode_GRPC {
		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)

View on GitHub (pinned to 0c51461d27)