grpc/grpc-go · error

fault: nil configuration message provided

Error message

fault: nil configuration message provided

What it means

parseConfig (fault.go:82) rejects a nil proto.Message up front. The fault filter requires an *anypb.Any wrapping an HTTPFault proto; a nil cfg means the xDS layer handed nothing to the parser, which is always a programming or control-plane error.

Solutions

1. Provide a non-nil *anypb.Any wrapping a populated fpb.HTTPFault proto to ParseFilterConfig.
2. Inspect the xDS Listener resource to confirm the fault filter's typed_config is present and has the correct type URL.
3. If fault injection is not desired, remove the filter from the Listener rather than sending nil.

Example fix

// before
fc, err := faultBuilder.ParseFilterConfig(nil)

// after
anyCfg, _ := anypb.New(&fpb.HTTPFault{Abort: &cpb.FaultAbort{...}})
fc, err := faultBuilder.ParseFilterConfig(anyCfg)

if cfg == nil {
    return nil, errors.New("fault: refusing to parse nil config")
}

fc, err := faultBuilder.ParseFilterConfig(anyCfg)
if err != nil {
    if strings.Contains(err.Error(), "nil configuration message") {
        // control-plane sent an empty fault filter entry; remove it or populate it
    }
    return err
}

When it happens

Trigger: ParseFilterConfig(nil) or ParseFilterConfigOverride(nil) is invoked, either directly or because the xDS resource contained a nil-typed config proto for the fault filter.

Common situations: xDS server emits a fault filter entry with an empty/absent config; programmatic registration of the filter with nil; test code that forgot to populate the config.

Related errors

• fault: error parsing config
• fault: error parsing config
• fault: incorrect config type provided (%T)
• fault: incorrect override config type provided (%T)
• fault: nil config provided

AI-assisted analysis of grpc/grpc-go@0c51461d27 (2026-08-11). Data as JSON: /api/errors/092a0d60418031ae. Report an issue: GitHub.

Appendix: source

Thrown at internal/xds/httpfilter/fault/fault.go:83

	httpfilter.Register(builder{})
}

type builder struct {
}

type config struct {
	httpfilter.FilterConfig
	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)

View on GitHub (pinned to 0c51461d27)