gofiber/fiber · error

fiber: shared state is not configured

Error message

fiber: shared state %s %s is not configured

What it means

Returned by sharedStateCodecNotConfiguredError() when the requested codec function is nil. newSharedState() sets defaults for JSON and XML encoders/decoders, but MsgPack and CBOR are left nil unless the app supplies them via Config.MsgPackEncoder/Decoder or Config.CBOREncoder/Decoder. Calling the corresponding SharedState method therefore has no codec to invoke.

Solutions

1. Provide Config.MsgPackEncoder/Decoder (e.g., shamaton/msgpack Marshal/Unmarshal) when using SetMsgPack/GetMsgPack.
2. Provide Config.CBOREncoder/Decoder (e.g., fxamacker/cbor Marshal/Unmarshal) when using SetCBOR/GetCBOR.
3. Alternatively, use the JSON or XML methods, which have built-in defaults.
4. Add a startup assertion that the needed codecs are non-nil.

Example fix

// before — using msgpack without configuring the codec
app := fiber.New(fiber.Config{
    SharedStorage: storage,
    // MsgPackEncoder/Decoder missing
})
app.State().Shared().SetMsgPack("k", v, 0)
// -> fiber: shared state msgpack encoder is not configured

// after — wire the codec
app := fiber.New(fiber.Config{
    SharedStorage:     storage,
    MsgPackEncoder:    msgpack.Marshal,
    MsgPackDecoder:    msgpack.Unmarshal,
})
app.State().Shared().SetMsgPack("k", v, 0)

// Assert at startup that the codecs you use are configured.
func requireCodecs(app *fiber.App, useMsgPack, useCBOR bool) error {
    cfg := app.Config()
    if useMsgPack && (cfg.MsgPackEncoder == nil || cfg.MsgPackDecoder == nil) {
        return errors.New("msgpack codec required but not configured")
    }
    if useCBOR && (cfg.CBOREncoder == nil || cfg.CBORDecoder == nil) {
        return errors.New("cbor codec required but not configured")
    }
    return nil
}

if err := app.State().Shared().SetMsgPack(k, v, ttl); err != nil {
    if strings.Contains(err.Error(), "is not configured") {
        log.Fatal("configure MsgPackEncoder/Decoder before using MsgPack shared state")
    }
    return err
}

When it happens

Trigger: Calling app.State().Shared().SetMsgPack/GetMsgPack without Config.MsgPackEncoder/Decoder set; or SetCBOR/GetCBOR without Config.CBOREncoder/Decoder set. The check fires before any encode/decode attempt, so no panic occurs.

Common situations: Adopting SharedState MsgPack/CBOR for performance without wiring the codec; assuming Fiber ships a default msgpack/cbor codec (it does not — only JSON and XML default); removing a codec config line during refactor.

Related errors

• fiber: failed to decode shared state
• fiber: failed to encode shared state
• binder: msgpack is not configured, please check docs…
• binder: must explicitly set up CBOR, please check docs…
• ErrSharedStorageNotConfigured

AI-assisted analysis of gofiber/fiber@a105acad6c (2026-08-11). Data as JSON: /api/errors/6436dfd17e1d5562. Report an issue: GitHub.

Appendix: source

Thrown at shared_state.go:405

		defer func() {
			recovered = recover()
		}()

		err = decoder(data, out)
	}()

	if recovered != nil {
		return sharedStateCodecPanicError("decode", format, recovered)
	}
	if err != nil {
		return fmt.Errorf("fiber: failed to decode shared state %s value: %w", format, err)
	}

	return nil
}

func sharedStateCodecNotConfiguredError(format, direction string) error {
	return fmt.Errorf("fiber: shared state %s %s is not configured", format, direction)
}

func sharedStateCodecPanicError(operation, format string, recovered any) error {
	if err, ok := recovered.(error); ok {
		return fmt.Errorf("fiber: failed to %s shared state %s value: %w", operation, format, err)
	}

	return fmt.Errorf("fiber: failed to %s shared state %s value: %v", operation, format, recovered)
}

func (s *SharedState) storageKey(key string) (string, bool) {
	if key == "" {
		return "", false
	}

	return s.prefix + hex.EncodeToString(utils.UnsafeBytes(key)), true
}

View on GitHub (pinned to a105acad6c)