grpc/grpc-go · error

fault: error parsing config

Error message

fault: error parsing config %v: %v

What it means

parseConfig (fault.go:90) successfully type-asserted *anypb.Any but UnmarshalTo into fpb.HTTPFault failed. Causes: the Any's type_url does not match HTTPFault, the serialized bytes are corrupt, or the wire schema differs from the linked proto version.

Solutions

1. Ensure the anypb.Any type_url is exactly type.googleapis.com/envoy.extensions.filters.http.fault.v3.HTTPFault.
2. Pin the go-control-plane dependency version to match between server and client.
3. Log the wrapped error to identify whether it is a type-URL mismatch or a wire-format decode error.

Example fix

// before
anyCfg := &anypb.Any{TypeUrl: "type.googleapis.com/envoy.extensions.filters.http.fault.v3.HTTPFaultLegacy", Value: raw}

// after
anyCfg := &anypb.Any{TypeUrl: "type.googleapis.com/envoy.extensions.filters.http.fault.v3.HTTPFault", Value: raw}

if m, ok := cfg.(*anypb.Any); ok {
    want := "type.googleapis.com/envoy.extensions.filters.http.fault.v3.HTTPFault"
    if m.TypeUrl != want {
        return nil, fmt.Errorf("fault: type_url %q != %q", m.TypeUrl, want)
    }
}

if err != nil && strings.Contains(err.Error(), "error parsing config") {
    // inspect the wrapped error to distinguish type-URL mismatch from wire corruption
}

When it happens

Trigger: anypb.Any with a mismatched type URL (e.g., a different filter's URL), truncated/malformed payload, or version skew where the server's HTTPFault schema differs from the client's compiled proto.

Common situations: Control-plane and data-plane built from different Envoy proto versions; corrupted config in transit; wrong filter config bound to the fault TypeURL.

Related errors

• extproc: failed to unmarshal config
• extproc: failed to unmarshal override
• fault: error parsing config
• fault: incorrect config type provided (%T)
• fault: incorrect override config type provided (%T)

AI-assisted analysis of grpc/grpc-go@0c51461d27 (2026-08-11). Data as JSON: /api/errors/877f305d9b5928fc. Report an issue: GitHub.

Appendix: source

Thrown at internal/xds/httpfilter/fault/fault.go:91

	config *fpb.HTTPFault
}

func (builder) TypeURLs() []string {
	return []string{"type.googleapis.com/envoy.extensions.filters.http.fault.v3.HTTPFault"}
}

// Parsing is the same for the base config and the override config.
func parseConfig(cfg proto.Message) (httpfilter.FilterConfig, error) {
	if cfg == nil {
		return nil, fmt.Errorf("fault: nil configuration message provided")
	}
	m, ok := cfg.(*anypb.Any)
	if !ok {
		return nil, fmt.Errorf("fault: error parsing config %v: unknown type %T", cfg, cfg)
	}
	msg := new(fpb.HTTPFault)
	if err := m.UnmarshalTo(msg); err != nil {
		return nil, fmt.Errorf("fault: error parsing config %v: %v", cfg, err)
	}
	return config{config: msg}, nil
}

func (builder) ParseFilterConfig(cfg proto.Message) (httpfilter.FilterConfig, error) {
	return parseConfig(cfg)
}

func (builder) ParseFilterConfigOverride(override proto.Message) (httpfilter.FilterConfig, error) {
	return parseConfig(override)
}

func (builder) IsTerminal() bool {
	return false
}

func (builder) BuildClientFilter(httpfilter.ClientFilterOptions) httpfilter.ClientFilter {
	return clientFilter{}

View on GitHub (pinned to 0c51461d27)