diff --git a/config/api_config.go b/config/api_config.go
index 25a77f6a..e68d73c4 100644
--- a/config/api_config.go
+++ b/config/api_config.go
@@ -1,3 +1,6 @@
+// Copyright (C) 2024, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
 package config
 
 import (
diff --git a/go.mod b/go.mod
index ab775f17..b01056da 100644
--- a/go.mod
+++ b/go.mod
@@ -3,9 +3,9 @@ module github.com/ava-labs/awm-relayer
 go 1.22.6
 
 require (
-	github.com/ava-labs/avalanchego v1.11.10
-	github.com/ava-labs/coreth v0.13.7
-	github.com/ava-labs/subnet-evm v0.6.8
+	github.com/ava-labs/avalanchego v1.11.11-0.20240813203340-ab83fb41528d
+	github.com/ava-labs/coreth v0.13.8-fixed-genesis-upgrade.0.20240813194342-7635a96aa180
+	github.com/ava-labs/subnet-evm v0.6.9-0.20240816202746-18633729a0cd
 	github.com/ava-labs/teleporter v1.0.6
 	github.com/aws/aws-sdk-go-v2 v1.30.5
 	github.com/aws/aws-sdk-go-v2/config v1.27.9
diff --git a/go.sum b/go.sum
index 7f23fd94..fe1cb1de 100644
--- a/go.sum
+++ b/go.sum
@@ -58,12 +58,12 @@ github.com/alexliesenfeld/health v0.8.0/go.mod h1:TfNP0f+9WQVWMQRzvMUjlws4ceXKEL
 github.com/allegro/bigcache v1.2.1-0.20190218064605-e24eb225f156 h1:eMwmnE/GDgah4HI848JfFxHt+iPb26b4zyfspmqY0/8=
 github.com/allegro/bigcache v1.2.1-0.20190218064605-e24eb225f156/go.mod h1:Cb/ax3seSYIx7SuZdm2G2xzfwmv3TPSk2ucNfQESPXM=
 github.com/armon/consul-api v0.0.0-20180202201655-eb2c6b5be1b6/go.mod h1:grANhF5doyWs3UAsr3K4I6qtAmlQcZDesFNEHPZAzj8=
-github.com/ava-labs/avalanchego v1.11.10 h1:QujciF5OEp5FwAoe/RciFF/i47rxU5rkEr6fVuUBS1Q=
-github.com/ava-labs/avalanchego v1.11.10/go.mod h1:POgZPryqe80OeHCDNrXrPOKoFre736iFuMgmUBeKaLc=
-github.com/ava-labs/coreth v0.13.7 h1:k8T9u/ROifl8f7oXjHRc1KvSISRl9txvy7gGVmHEz6g=
-github.com/ava-labs/coreth v0.13.7/go.mod h1:tXDujonxXFOF6oK5HS2EmgtSXJK3Gy6RpZxb5WzR9rM=
-github.com/ava-labs/subnet-evm v0.6.8 h1:IrHGajBYWs692YIYdd5J0oVWWt88Q/XAZQq/dOtkHFw=
-github.com/ava-labs/subnet-evm v0.6.8/go.mod h1:qt8DXyGm40CY9yffNOe1+4yUyL9mD3v5RPWqAuGj5u4=
+github.com/ava-labs/avalanchego v1.11.11-0.20240813203340-ab83fb41528d h1:LyrKJL9avIIxBY3uTcS2dFtUMBFmI2QpAgG6qYTdA6s=
+github.com/ava-labs/avalanchego v1.11.11-0.20240813203340-ab83fb41528d/go.mod h1:UkyrRDXK2E15Lq2abyae2Pt+JsWvgsg1pe0/AtoMyAM=
+github.com/ava-labs/coreth v0.13.8-fixed-genesis-upgrade.0.20240813194342-7635a96aa180 h1:6aIHp7wbyGVYdhHVQUbG7BEcbCMEQ5SYopPPJyipyvk=
+github.com/ava-labs/coreth v0.13.8-fixed-genesis-upgrade.0.20240813194342-7635a96aa180/go.mod h1:/wNBVq7J7wlC2Kbov7kk6LV5xZvau7VF9zwTVOeyAjY=
+github.com/ava-labs/subnet-evm v0.6.9-0.20240816202746-18633729a0cd h1:5kJTOhmIhIiobseQ+RYuLg4UyodN+CSAdW1c0hx1R2Y=
+github.com/ava-labs/subnet-evm v0.6.9-0.20240816202746-18633729a0cd/go.mod h1:QfIzh7YxKj97jbendOHQbaAxM7SMj5MWdV13o1VLn70=
 github.com/ava-labs/teleporter v1.0.6 h1:buZULenvJLUUMyPihiSvGMag5/rm6oF8zL8YUw7NXxE=
 github.com/ava-labs/teleporter v1.0.6/go.mod h1:JRfVZzLrb4qFZz2M5/c8L7cdN4A4JWJd7GIEzVeC+sg=
 github.com/aws/aws-sdk-go-v2 v1.30.5 h1:mWSRTwQAb0aLE17dSzztCVJWI9+cRMgqebndjwDyK0g=
diff --git a/peers/external_handler.go b/peers/external_handler.go
index 7b6417ce..be4e0518 100644
--- a/peers/external_handler.go
+++ b/peers/external_handler.go
@@ -90,6 +90,9 @@ func (h *RelayerExternalHandler) HandleInbound(_ context.Context, inboundMessage
 		zap.Stringer("from", inboundMessage.NodeID()),
 	)
 	if inboundMessage.Op() == message.AppResponseOp || inboundMessage.Op() == message.AppErrorOp {
+		if inboundMessage.Op() == message.AppErrorOp {
+			h.log.Debug("Received AppError message", zap.Stringer("message", inboundMessage.Message()))
+		}
 		h.registerAppResponse(inboundMessage)
 	} else {
 		h.log.Debug("Ignoring message", zap.Stringer("op", inboundMessage.Op()))
diff --git a/relayer/application_relayer.go b/relayer/application_relayer.go
index 89a33194..c1c93910 100644
--- a/relayer/application_relayer.go
+++ b/relayer/application_relayer.go
@@ -204,6 +204,7 @@ func (r *ApplicationRelayer) ProcessMessage(handler messages.MessageHandler) (co
 	if r.sourceWarpSignatureClient == nil {
 		signedMessage, err = r.signatureAggregator.CreateSignedMessage(
 			unsignedMessage,
+			nil,
 			r.signingSubnetID,
 			r.warpQuorum.QuorumNumerator,
 		)
diff --git a/relayer/config/config.go b/relayer/config/config.go
index 57ea0822..3f643dd2 100644
--- a/relayer/config/config.go
+++ b/relayer/config/config.go
@@ -8,6 +8,7 @@ import (
 	"errors"
 	"fmt"
 	"net/url"
+	"time"
 
 	basecfg "github.com/ava-labs/awm-relayer/config"
 	"github.com/ava-labs/awm-relayer/peers"
@@ -67,6 +68,9 @@ type Config struct {
 	DeciderURL             string                   `mapstructure:"decider-url" json:"decider-url"`
 	SignatureCacheSize     uint64                   `mapstructure:"signature-cache-size" json:"signature-cache-size"`
 
+	// mapstructure doesn't handle time.Time out of the box so handle it manually
+	EtnaTime time.Time `json:"etna-time"`
+
 	// convenience field to fetch a blockchain's subnet ID
 	blockchainIDToSubnetID map[ids.ID]ids.ID
 	overwrittenOptions     []string
diff --git a/relayer/config/keys.go b/relayer/config/keys.go
index 1c426fe0..fa211fc2 100644
--- a/relayer/config/keys.go
+++ b/relayer/config/keys.go
@@ -24,4 +24,5 @@ const (
 	ManualWarpMessagesKey     = "manual-warp-messages"
 	DBWriteIntervalSecondsKey = "db-write-interval-seconds"
 	SignatureCacheSizeKey     = "signature-cache-size"
+	EtnaTimeKey               = "etna-time"
 )
diff --git a/relayer/config/viper.go b/relayer/config/viper.go
index 507bd952..4e0e279b 100644
--- a/relayer/config/viper.go
+++ b/relayer/config/viper.go
@@ -84,6 +84,9 @@ func BuildConfig(v *viper.Viper) (Config, error) {
 		return cfg, fmt.Errorf("failed to unmarshal viper config: %w", err)
 	}
 
+	// Manually set EtnaTime field since it's not automatically parseable using mapstructure
+	cfg.EtnaTime = v.GetTime(EtnaTimeKey)
+
 	// Explicitly overwrite the configured account private key
 	// If account-private-key is set as a flag or environment variable,
 	// overwrite all destination subnet configurations to use that key
diff --git a/relayer/main/main.go b/relayer/main/main.go
index 95d25a4b..06e4c6e5 100644
--- a/relayer/main/main.go
+++ b/relayer/main/main.go
@@ -227,6 +227,7 @@ func main() {
 			prometheus.DefaultRegisterer,
 		),
 		messageCreator,
+		cfg.EtnaTime,
 	)
 	if err != nil {
 		logger.Fatal("Failed to create signature aggregator", zap.Error(err))
diff --git a/scripts/versions.sh b/scripts/versions.sh
index 641974a9..018f5d67 100755
--- a/scripts/versions.sh
+++ b/scripts/versions.sh
@@ -17,12 +17,14 @@ function getDepVersion() {
 export GO_VERSION=${GO_VERSION:-$(getDepVersion go)}
 
 # Don't export them as they're used in the context of other calls
-AVALANCHEGO_VERSION=${AVALANCHEGO_VERSION:-$(getDepVersion github.com/ava-labs/avalanchego)}
+# TODO: undo this hack once go.mod is referring to a tag rather than a commit
+#AVALANCHEGO_VERSION=${AVALANCHEGO_VERSION:-$(getDepVersion github.com/ava-labs/avalanchego)}
+AVALANCHEGO_VERSION=${AVALANCHEGO_VERSION:-ab83fb41528de93c1790301cdd67a07dda9299f0}
 GINKGO_VERSION=${GINKGO_VERSION:-$(getDepVersion github.com/onsi/ginkgo/v2)}
 
 # TODO: undo this hack once go.mod is referring to a tag rather than a commit
 #SUBNET_EVM_VERSION=${SUBNET_EVM_VERSION:-$(getDepVersion github.com/ava-labs/subnet-evm)}
-SUBNET_EVM_VERSION=${SUBNET_EVM_VERSION:-update-avago-teleporter}
+SUBNET_EVM_VERSION=${SUBNET_EVM_VERSION:-18633729a0cde7d695616e14b77873957a2b59c2}
 
 # Set golangci-lint version
 GOLANGCI_LINT_VERSION=${GOLANGCI_LINT_VERSION:-'v1.60'}
diff --git a/signature-aggregator/README.md b/signature-aggregator/README.md
index 1c8b60a1..ed6e9e97 100644
--- a/signature-aggregator/README.md
+++ b/signature-aggregator/README.md
@@ -69,9 +69,9 @@ curl --location 'https://api.avax-test.network/ext/bc/C/rpc' \
    The topic of the message will be `0x56600c567728a800c0aa927500f831cb451df66a7af570eb4df4dfbf4674887d` which is the output of`cast keccak "SendWarpMessage(address,bytes32,bytes)"`
 4. Use the data field of the log message found in step 2 and send it to the locally running service via curl.
 ```bash
-curl --location 'http://localhost:8080/aggregate-signatures/by-raw-message' \
+curl --location 'http://localhost:8080/aggregate-signatures' \
 --header 'Content-Type: application/json' \
 --data '{
-    "data": "<hex encoded unsigned message bytes retrieved from the logs>",
+    "message": "<hex encoded unsigned message bytes retrieved from the logs>"
 }'
 ```
diff --git a/signature-aggregator/aggregator/aggregator.go b/signature-aggregator/aggregator/aggregator.go
index a48ac728..a284c224 100644
--- a/signature-aggregator/aggregator/aggregator.go
+++ b/signature-aggregator/aggregator/aggregator.go
@@ -15,7 +15,9 @@ import (
 
 	"github.com/ava-labs/avalanchego/ids"
 	"github.com/ava-labs/avalanchego/message"
+	networkP2P "github.com/ava-labs/avalanchego/network/p2p"
 	"github.com/ava-labs/avalanchego/proto/pb/p2p"
+	"github.com/ava-labs/avalanchego/proto/pb/sdk"
 	"github.com/ava-labs/avalanchego/subnets"
 	"github.com/ava-labs/avalanchego/utils/constants"
 	"github.com/ava-labs/avalanchego/utils/crypto/bls"
@@ -26,9 +28,10 @@ import (
 	"github.com/ava-labs/awm-relayer/signature-aggregator/aggregator/cache"
 	"github.com/ava-labs/awm-relayer/signature-aggregator/metrics"
 	"github.com/ava-labs/awm-relayer/utils"
-	coreEthMsg "github.com/ava-labs/coreth/plugin/evm/message"
+	corethMsg "github.com/ava-labs/coreth/plugin/evm/message"
 	msg "github.com/ava-labs/subnet-evm/plugin/evm/message"
 	"go.uber.org/zap"
+	"google.golang.org/protobuf/proto"
 )
 
 type blsSignatureBuf [bls.SignatureLen]byte
@@ -42,8 +45,8 @@ const (
 )
 
 var (
-	codec        = msg.Codec
-	coreEthCodec = coreEthMsg.Codec
+	codec       = msg.Codec
+	corethCodec = corethMsg.Codec
 
 	// Errors
 	errNotEnoughSignatures     = errors.New("failed to collect a threshold of signatures")
@@ -60,6 +63,7 @@ type SignatureAggregator struct {
 	subnetsMapLock          sync.RWMutex
 	metrics                 *metrics.SignatureAggregatorMetrics
 	cache                   *cache.Cache
+	etnaTime                time.Time
 }
 
 func NewSignatureAggregator(
@@ -68,6 +72,7 @@ func NewSignatureAggregator(
 	signatureCacheSize uint64,
 	metrics *metrics.SignatureAggregatorMetrics,
 	messageCreator message.Creator,
+	etnaTime time.Time,
 ) (*SignatureAggregator, error) {
 	cache, err := cache.NewCache(signatureCacheSize, logger)
 	if err != nil {
@@ -84,6 +89,7 @@ func NewSignatureAggregator(
 		messageCreator:          messageCreator,
 		currentRequestID:        atomic.Uint32{},
 		cache:                   cache,
+		etnaTime:                etnaTime,
 	}
 	sa.currentRequestID.Store(rand.Uint32())
 	return &sa, nil
@@ -91,6 +97,7 @@ func NewSignatureAggregator(
 
 func (s *SignatureAggregator) CreateSignedMessage(
 	unsignedMessage *avalancheWarp.UnsignedMessage,
+	justification []byte,
 	inputSigningSubnet ids.ID,
 	quorumPercentage uint64,
 ) (*avalancheWarp.Message, error) {
@@ -176,19 +183,7 @@ func (s *SignatureAggregator) CreateSignedMessage(
 		))
 	}
 
-	// TODO: remove this special handling and replace with ACP-118 interface once available
-	var reqBytes []byte
-	if sourceSubnet == constants.PrimaryNetworkID {
-		req := coreEthMsg.MessageSignatureRequest{
-			MessageID: unsignedMessage.ID(),
-		}
-		reqBytes, err = coreEthMsg.RequestToBytes(coreEthCodec, req)
-	} else {
-		req := msg.MessageSignatureRequest{
-			MessageID: unsignedMessage.ID(),
-		}
-		reqBytes, err = msg.RequestToBytes(codec, req)
-	}
+	reqBytes, err := s.marshalRequest(unsignedMessage, justification, sourceSubnet)
 	if err != nil {
 		msg := "Failed to marshal request bytes"
 		s.logger.Error(
@@ -524,14 +519,13 @@ func (s *SignatureAggregator) isValidSignatureResponse(
 		return blsSignatureBuf{}, false
 	}
 
-	var sigResponse msg.SignatureResponse
-	if _, err := msg.Codec.Unmarshal(appResponse.AppBytes, &sigResponse); err != nil {
+	signature, err := s.unmarshalResponse(appResponse.AppBytes)
+	if err != nil {
 		s.logger.Error(
 			"Error unmarshaling signature response",
 			zap.Error(err),
 		)
 	}
-	signature := sigResponse.Signature
 
 	// If the node returned an empty signature, then it has not yet seen the warp message. Retry later.
 	emptySignature := blsSignatureBuf{}
@@ -543,6 +537,15 @@ func (s *SignatureAggregator) isValidSignatureResponse(
 		return blsSignatureBuf{}, false
 	}
 
+	if len(signature) != bls.SignatureLen {
+		s.logger.Debug(
+			"Response signature has incorrect length",
+			zap.Int("actual", len(signature)),
+			zap.Int("expected", bls.SignatureLen),
+		)
+		return blsSignatureBuf{}, false
+	}
+
 	sig, err := bls.SignatureFromBytes(signature[:])
 	if err != nil {
 		s.logger.Debug(
@@ -590,3 +593,65 @@ func (s *SignatureAggregator) aggregateSignatures(
 	}
 	return aggSig, vdrBitSet, nil
 }
+
+// TODO: refactor this to remove special handling based on etnaTime
+// after Etna release, along with related config and testing code
+func (s *SignatureAggregator) marshalRequest(
+	unsignedMessage *avalancheWarp.UnsignedMessage,
+	justification []byte,
+	sourceSubnet ids.ID,
+) ([]byte, error) {
+	if s.etnaActivated() {
+		// Post-Etna case
+		messageBytes, err := proto.Marshal(
+			&sdk.SignatureRequest{
+				Message:       unsignedMessage.Bytes(),
+				Justification: justification,
+			},
+		)
+		if err != nil {
+			return nil, err
+		}
+		return networkP2P.PrefixMessage(
+			networkP2P.ProtocolPrefix(networkP2P.SignatureRequestHandlerID),
+			messageBytes,
+		), nil
+	} else {
+		// Pre-Etna case
+		if sourceSubnet == constants.PrimaryNetworkID {
+			req := corethMsg.MessageSignatureRequest{
+				MessageID: unsignedMessage.ID(),
+			}
+			return corethMsg.RequestToBytes(corethCodec, req)
+		} else {
+			req := msg.MessageSignatureRequest{
+				MessageID: unsignedMessage.ID(),
+			}
+			return msg.RequestToBytes(codec, req)
+		}
+	}
+}
+
+func (s *SignatureAggregator) unmarshalResponse(responseBytes []byte) (blsSignatureBuf, error) {
+	if s.etnaActivated() {
+		// Post-Etna case
+		var sigResponse sdk.SignatureResponse
+		err := proto.Unmarshal(responseBytes, &sigResponse)
+		if err != nil {
+			return blsSignatureBuf{}, err
+		}
+		return blsSignatureBuf(sigResponse.Signature), nil
+	} else {
+		// Pre-Etna case
+		var sigResponse msg.SignatureResponse
+		_, err := msg.Codec.Unmarshal(responseBytes, &sigResponse)
+		if err != nil {
+			return blsSignatureBuf{}, err
+		}
+		return sigResponse.Signature, nil
+	}
+}
+
+func (s *SignatureAggregator) etnaActivated() bool {
+	return !s.etnaTime.IsZero() && s.etnaTime.Before(time.Now())
+}
diff --git a/signature-aggregator/aggregator/aggregator_test.go b/signature-aggregator/aggregator/aggregator_test.go
index 13a6952c..8876a646 100644
--- a/signature-aggregator/aggregator/aggregator_test.go
+++ b/signature-aggregator/aggregator/aggregator_test.go
@@ -2,6 +2,7 @@ package aggregator
 
 import (
 	"testing"
+	"time"
 
 	"github.com/ava-labs/avalanchego/ids"
 	"github.com/ava-labs/avalanchego/message"
@@ -43,6 +44,8 @@ func instantiateAggregator(t *testing.T) (
 		1024,
 		sigAggMetrics,
 		messageCreator,
+		// Setting the etnaTime to a minute ago so that the post-etna code path is used in the test
+		time.Now().Add(-1*time.Minute),
 	)
 	require.Equal(t, err, nil)
 	return aggregator, mockNetwork
@@ -61,7 +64,7 @@ func TestCreateSignedMessageFailsWithNoValidators(t *testing.T) {
 		},
 		nil,
 	)
-	_, err = aggregator.CreateSignedMessage(msg, ids.Empty, 80)
+	_, err = aggregator.CreateSignedMessage(msg, nil, ids.Empty, 80)
 	require.ErrorContains(t, err, "no signatures")
 }
 
@@ -78,7 +81,7 @@ func TestCreateSignedMessageFailsWithoutSufficientConnectedStake(t *testing.T) {
 		},
 		nil,
 	)
-	_, err = aggregator.CreateSignedMessage(msg, ids.Empty, 80)
+	_, err = aggregator.CreateSignedMessage(msg, nil, ids.Empty, 80)
 	require.ErrorContains(
 		t,
 		err,
diff --git a/signature-aggregator/api/api.go b/signature-aggregator/api/api.go
index e5a5829b..1717b3a9 100644
--- a/signature-aggregator/api/api.go
+++ b/signature-aggregator/api/api.go
@@ -26,8 +26,11 @@ const (
 
 // Defines a request interface for signature aggregation for a raw unsigned message.
 type AggregateSignatureRequest struct {
-	// Required. hex-encoded message, optionally prefixed with "0x".
-	UnsignedMessage string `json:"unsigned-message"`
+	// Required: either Message or Justification must be provided.
+	// hex-encoded message, optionally prefixed with "0x".
+	Message string `json:"message"`
+	// hex-encoded justification, optionally prefixed with "0x".
+	Justification string `json:"justification"`
 	// Optional hex or cb58 encoded signing subnet ID. If omitted will default to the subnetID of the source blockchain
 	SigningSubnetID string `json:"signing-subnet-id"`
 	// Optional. Integer from 0 to 100 representing the percentage of the quorum that is required to sign the message
@@ -75,6 +78,15 @@ func writeJSONError(
 	}
 }
 
+func isEmptyOrZeroes(bytes []byte) bool {
+	for _, b := range bytes {
+		if b != 0 {
+			return false
+		}
+	}
+	return true
+}
+
 func signatureAggregationAPIHandler(
 	logger logging.Logger,
 	metrics *metrics.SignatureAggregatorMetrics,
@@ -94,25 +106,49 @@ func signatureAggregationAPIHandler(
 		}
 		var decodedMessage []byte
 		decodedMessage, err = hex.DecodeString(
-			strings.TrimPrefix(req.UnsignedMessage, "0x"),
+			strings.TrimPrefix(req.Message, "0x"),
 		)
 		if err != nil {
 			msg := "Could not decode message"
 			logger.Warn(
 				msg,
-				zap.String("msg", req.UnsignedMessage),
+				zap.String("msg", req.Message),
 				zap.Error(err),
 			)
 			writeJSONError(logger, w, msg)
 			return
 		}
-		unsignedMessage, err := types.UnpackWarpMessage(decodedMessage)
+		message, err := types.UnpackWarpMessage(decodedMessage)
 		if err != nil {
 			msg := "Error unpacking warp message"
 			logger.Warn(msg, zap.Error(err))
 			writeJSONError(logger, w, msg)
 			return
 		}
+
+		justification, err := hex.DecodeString(
+			utils.SanitizeHexString(req.Justification),
+		)
+		if err != nil {
+			msg := "Could not decode justification"
+			logger.Warn(
+				msg,
+				zap.String("justification", req.Justification),
+				zap.Error(err),
+			)
+			writeJSONError(logger, w, msg)
+			return
+		}
+
+		if isEmptyOrZeroes(message.Bytes()) && isEmptyOrZeroes(justification) {
+			writeJSONError(
+				logger,
+				w,
+				"Must provide either message or justification",
+			)
+			return
+		}
+
 		quorumPercentage := req.QuorumPercentage
 		if quorumPercentage == 0 {
 			quorumPercentage = DefaultQuorumPercentage
@@ -140,7 +176,8 @@ func signatureAggregationAPIHandler(
 		}
 
 		signedMessage, err := aggregator.CreateSignedMessage(
-			unsignedMessage,
+			message,
+			justification,
 			signingSubnetID,
 			quorumPercentage,
 		)
diff --git a/signature-aggregator/config/config.go b/signature-aggregator/config/config.go
index 19b769d2..ec6d570e 100644
--- a/signature-aggregator/config/config.go
+++ b/signature-aggregator/config/config.go
@@ -5,6 +5,7 @@ package config
 
 import (
 	"fmt"
+	"time"
 
 	"github.com/ava-labs/avalanchego/utils/logging"
 	basecfg "github.com/ava-labs/awm-relayer/config"
@@ -34,6 +35,9 @@ type Config struct {
 	APIPort            uint16             `mapstructure:"api-port" json:"api-port"`
 	MetricsPort        uint16             `mapstructure:"metrics-port" json:"metrics-port"`
 	SignatureCacheSize uint64             `mapstructure:"signature-cache-size" json:"signature-cache-size"`
+
+	// mapstructure doesn't support time.Time out of the box so handle it manually
+	EtnaTime time.Time `json:"etna-time"`
 }
 
 func DisplayUsageText() {
diff --git a/signature-aggregator/config/keys.go b/signature-aggregator/config/keys.go
index 97829f77..d2f3e077 100644
--- a/signature-aggregator/config/keys.go
+++ b/signature-aggregator/config/keys.go
@@ -16,4 +16,5 @@ const (
 	APIPortKey            = "api-port"
 	MetricsPortKey        = "metrics-port"
 	SignatureCacheSizeKey = "signature-cache-size"
+	EtnaTimeKey           = "etna-time"
 )
diff --git a/signature-aggregator/config/viper.go b/signature-aggregator/config/viper.go
index dc33f918..0ca4a410 100644
--- a/signature-aggregator/config/viper.go
+++ b/signature-aggregator/config/viper.go
@@ -76,5 +76,8 @@ func BuildConfig(v *viper.Viper) (Config, error) {
 		return cfg, fmt.Errorf("failed to unmarshal viper config: %w", err)
 	}
 
+	// mapstructure doesn't support time.Time out of the box so handle it manually
+	cfg.EtnaTime = v.GetTime(EtnaTimeKey)
+
 	return cfg, nil
 }
diff --git a/signature-aggregator/main/main.go b/signature-aggregator/main/main.go
index 69b619a1..27edfd3b 100644
--- a/signature-aggregator/main/main.go
+++ b/signature-aggregator/main/main.go
@@ -117,6 +117,7 @@ func main() {
 		cfg.SignatureCacheSize,
 		metricsInstance,
 		messageCreator,
+		cfg.EtnaTime,
 	)
 	if err != nil {
 		logger.Fatal("Failed to create signature aggregator", zap.Error(err))
diff --git a/tests/e2e_test.go b/tests/e2e_test.go
index 48a61808..4a475334 100644
--- a/tests/e2e_test.go
+++ b/tests/e2e_test.go
@@ -174,4 +174,7 @@ var _ = ginkgo.Describe("[AWM Relayer Integration Tests", func() {
 	ginkgo.It("Signature Aggregator", func() {
 		SignatureAggregatorAPI(localNetworkInstance)
 	})
+	ginkgo.It("Etna Upgrade", func() {
+		EtnaUpgrade(localNetworkInstance)
+	})
 })
diff --git a/tests/etna_upgrade.go b/tests/etna_upgrade.go
new file mode 100644
index 00000000..02ab768c
--- /dev/null
+++ b/tests/etna_upgrade.go
@@ -0,0 +1,94 @@
+// Copyright (C) 2024, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package tests
+
+import (
+	"context"
+	"time"
+
+	testUtils "github.com/ava-labs/awm-relayer/tests/utils"
+	"github.com/ava-labs/teleporter/tests/interfaces"
+	"github.com/ava-labs/teleporter/tests/utils"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/log"
+	. "github.com/onsi/gomega"
+)
+
+// This tests basic functionality of the relayer post-etna upgrade
+// since other tests write zero value of time.Time
+// to the config  and therefore are testing the pre-etna case
+// - Relaying from Subnet A to Subnet B
+// - Relaying from Subnet B to Subnet A
+func EtnaUpgrade(network interfaces.LocalNetwork) {
+	subnetAInfo := network.GetPrimaryNetworkInfo()
+	subnetBInfo, _ := utils.GetTwoSubnets(network)
+	fundedAddress, fundedKey := network.GetFundedAccountInfo()
+	teleporterContractAddress := network.GetTeleporterContractAddress()
+	err := testUtils.ClearRelayerStorage()
+	Expect(err).Should(BeNil())
+	//
+	// Fund the relayer address on all subnets
+	//
+	ctx := context.Background()
+
+	log.Info("Funding relayer address on all subnets")
+	relayerKey, err := crypto.GenerateKey()
+	Expect(err).Should(BeNil())
+	testUtils.FundRelayers(ctx, []interfaces.SubnetTestInfo{subnetAInfo, subnetBInfo}, fundedKey, relayerKey)
+
+	//
+	// Set up relayer config
+	//
+	relayerConfig := testUtils.CreateDefaultRelayerConfig(
+		[]interfaces.SubnetTestInfo{subnetAInfo, subnetBInfo},
+		[]interfaces.SubnetTestInfo{subnetAInfo, subnetBInfo},
+		teleporterContractAddress,
+		fundedAddress,
+		relayerKey,
+	)
+	// Setting the EtnaTime to yesterday so that the post-etna logic path is used.
+	relayerConfig.EtnaTime = time.Now().AddDate(0, 0, -1)
+	// The config needs to be validated in order to be passed to database.GetConfigRelayerIDs
+	relayerConfig.Validate()
+
+	relayerConfigPath := testUtils.WriteRelayerConfig(relayerConfig, testUtils.DefaultRelayerCfgFname)
+
+	//
+	// Test Relaying from Subnet A to Subnet B
+	//
+	log.Info("Test Relaying from Subnet A to Subnet B")
+
+	log.Info("Starting the relayer")
+	relayerCleanup, readyChan := testUtils.RunRelayerExecutable(
+		ctx,
+		relayerConfigPath,
+		relayerConfig,
+	)
+	defer relayerCleanup()
+
+	// Wait for relayer to start up
+	startupCtx, startupCancel := context.WithTimeout(ctx, 15*time.Second)
+	defer startupCancel()
+	testUtils.WaitForChannelClose(startupCtx, readyChan)
+
+	log.Info("Sending transaction from Subnet A to Subnet B")
+	testUtils.RelayBasicMessage(
+		ctx,
+		subnetAInfo,
+		subnetBInfo,
+		teleporterContractAddress,
+		fundedKey,
+		fundedAddress,
+	)
+
+	log.Info("Test Relaying from Subnet B to Subnet A")
+	testUtils.RelayBasicMessage(
+		ctx,
+		subnetBInfo,
+		subnetAInfo,
+		teleporterContractAddress,
+		fundedKey,
+		fundedAddress,
+	)
+}
diff --git a/tests/signature_aggregator_api.go b/tests/signature_aggregator_api.go
index 4b00c23d..2e26855e 100644
--- a/tests/signature_aggregator_api.go
+++ b/tests/signature_aggregator_api.go
@@ -79,7 +79,7 @@ func SignatureAggregatorAPI(network interfaces.LocalNetwork) {
 	warpMessage := getWarpMessageFromLog(ctx, receipt, subnetAInfo)
 
 	reqBody := api.AggregateSignatureRequest{
-		UnsignedMessage: "0x" + hex.EncodeToString(warpMessage.Bytes()),
+		Message: "0x" + hex.EncodeToString(warpMessage.Bytes()),
 	}
 
 	client := http.Client{