diff --git a/messages.go b/messages.go
index 0a9c2f4..109fd32 100644
--- a/messages.go
+++ b/messages.go
@@ -194,7 +194,7 @@ func (msg *Message) From() string {
 }
 
 func (msg *Message) IsTransactionPart() bool {
-	return msg.Type.SupportsTransaction() && len(msg.TransactionUUID) > 0
+	return msg.Type.RequiresTransaction() && len(msg.TransactionUUID) > 0
 }
 
 func (msg *Message) TransactionKey() string {
diff --git a/messages_test.go b/messages_test.go
index a5f88b1..0401766 100644
--- a/messages_test.go
+++ b/messages_test.go
@@ -114,7 +114,7 @@ func testMessageRoutable(t *testing.T, original Message) {
 	assert.Equal(original.Source, original.From())
 	assert.Equal(original.TransactionUUID, original.TransactionKey())
 	assert.Equal(
-		original.Type.SupportsTransaction() && len(original.TransactionUUID) > 0,
+		original.Type.RequiresTransaction() && len(original.TransactionUUID) > 0,
 		original.IsTransactionPart(),
 	)
 
diff --git a/messagetype.go b/messagetype.go
index 36163ae..5feaf04 100644
--- a/messagetype.go
+++ b/messagetype.go
@@ -44,10 +44,10 @@ const (
 	lastMessageType
 )
 
-// SupportsTransaction tests if messages of this type are allowed to participate in transactions.
+// RequiresTransaction tests if messages of this type are allowed to participate in transactions.
 // If this method returns false, the TransactionUUID field should be ignored (but passed through
-// where applicable).
-func (mt MessageType) SupportsTransaction() bool {
+// where applicable). If this method returns true, TransactionUUID must be included in request.
+func (mt MessageType) RequiresTransaction() bool {
 	switch mt {
 	case SimpleRequestResponseMessageType, CreateMessageType, RetrieveMessageType, UpdateMessageType, DeleteMessageType:
 		return true
diff --git a/messagetype_test.go b/messagetype_test.go
index 068ed45..4090395 100644
--- a/messagetype_test.go
+++ b/messagetype_test.go
@@ -79,7 +79,7 @@ func TestMessageTypeSupportsTransaction(t *testing.T) {
 	)
 
 	for messageType, expected := range expectedSupportsTransaction {
-		assert.Equal(expected, messageType.SupportsTransaction())
+		assert.Equal(expected, messageType.RequiresTransaction())
 	}
 }
 
diff --git a/wrphttp/handler.go b/wrphttp/handler.go
index 6248a78..33b726d 100644
--- a/wrphttp/handler.go
+++ b/wrphttp/handler.go
@@ -18,6 +18,7 @@
 package wrphttp
 
 import (
+	"fmt"
 	"net/http"
 
 	gokithttp "github.com/go-kit/kit/transport/http"
@@ -128,6 +129,15 @@ func (wh *wrpHandler) ServeHTTP(httpResponse http.ResponseWriter, httpRequest *h
 		return
 	}
 
+	if entity.Message.Type.RequiresTransaction() && entity.Message.TransactionUUID == "" {
+		wrappedErr := httpError{
+			err:  fmt.Errorf("%s", string(entity.Bytes)),
+			code: http.StatusBadRequest,
+		}
+		wh.errorEncoder(ctx, wrappedErr, httpResponse)
+		return
+	}
+
 	for _, mf := range wh.before {
 		ctx = mf(ctx, &entity.Message)
 	}
diff --git a/wrphttp/handler_test.go b/wrphttp/handler_test.go
index 56fd9d6..5c5a772 100644
--- a/wrphttp/handler_test.go
+++ b/wrphttp/handler_test.go
@@ -19,6 +19,7 @@ package wrphttp
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"net/http"
@@ -270,6 +271,58 @@ func testWRPHandlerDecodeError(t *testing.T) {
 	wrpHandler.AssertExpectations(t)
 }
 
+func testTransactionUUIDError(t *testing.T) {
+	var (
+		assert  = assert.New(t)
+		require = require.New(t)
+
+		msg = wrp.Message{
+			Type: wrp.SimpleRequestResponseMessageType,
+		}
+		msgBytes, _ = json.Marshal(msg)
+		entity      = &Entity{
+			Message: msg,
+			Bytes:   msgBytes,
+		}
+
+		expectedError = httpError{
+			err:  fmt.Errorf("%s", string(entity.Bytes)),
+			code: http.StatusBadRequest,
+		}
+		decoder = func(_ context.Context, _ *http.Request) (*Entity, error) {
+			return entity, nil
+		}
+
+		errorEncoderCalled = false
+		httpResponse       = httptest.NewRecorder()
+	)
+
+	httpRequest := httptest.NewRequest("POST", "/", nil)
+
+	errorEncoder := func(_ context.Context, actualErr error, _ http.ResponseWriter) {
+		errorEncoderCalled = true
+		assert.Equal(expectedError, actualErr)
+
+		var actualErrorHTTP httpError
+		if assert.ErrorAs(actualErr, &actualErrorHTTP,
+			fmt.Errorf("error [%v] doesn't contain error [%v] in its err chain",
+				actualErr, actualErrorHTTP)) {
+			assert.Equal(expectedError.code, actualErrorHTTP.code)
+		}
+	}
+
+	wrpHandler := new(MockHandler)
+	httpHandler := NewHTTPHandler(wrpHandler,
+		WithDecoder(decoder),
+		WithErrorEncoder(errorEncoder))
+
+	require.NotNil(httpHandler)
+	httpHandler.ServeHTTP(httpResponse, httpRequest)
+
+	assert.True(errorEncoderCalled)
+
+}
+
 func testWRPHandlerResponseWriterError(t *testing.T) {
 	var (
 		assert  = assert.New(t)
@@ -386,5 +439,6 @@ func TestWRPHandler(t *testing.T) {
 		t.Run("DecodeError", testWRPHandlerDecodeError)
 		t.Run("ResponseWriterError", testWRPHandlerResponseWriterError)
 		t.Run("Success", testWRPHandlerSuccess)
+		t.Run("TransactionUUIDError", testTransactionUUIDError)
 	})
 }