diff --git a/pkg/xerr/catalog.go b/pkg/xerr/catalog.go
index b1015397..42d09235 100644
--- a/pkg/xerr/catalog.go
+++ b/pkg/xerr/catalog.go
@@ -62,7 +62,7 @@ var catalog = map[Code]Spec{
 	RegionNotFound:        spec(codes.NotFound, httpStatusNotFound, RegionNotFound, "not found"),
 	RegionCountryConflict: spec(codes.FailedPrecondition, httpStatusConflict, RegionCountryConflict, "conflict"),
 	RegionDisabled:        spec(codes.FailedPrecondition, httpStatusConflict, RegionDisabled, "conflict"),
-	InvalidInviteCode:     spec(codes.InvalidArgument, httpStatusBadRequest, InvalidInviteCode, "invalid argument"),
+	InvalidInviteCode:     spec(codes.InvalidArgument, httpStatusBadRequest, InvalidInviteCode, "invalid invite code"),
 	DeviceAlreadyRegistered: spec(
 		codes.FailedPrecondition,
 		httpStatusConflict,
diff --git a/pkg/xerr/grpc_test.go b/pkg/xerr/grpc_test.go
index 41f36d3f..2e9a535c 100644
--- a/pkg/xerr/grpc_test.go
+++ b/pkg/xerr/grpc_test.go
@@ -60,7 +60,7 @@ func TestCatalogMappings(t *testing.T) {
 			grpcCode:      codes.InvalidArgument,
 			httpStatus:    httpStatusBadRequest,
 			publicCode:    string(InvalidInviteCode),
-			publicMessage: "invalid argument",
+			publicMessage: "invalid invite code",
 		},
 		{
 			name:          "unavailable is exposed as upstream error",
diff --git a/services/gateway-service/internal/transport/http/response_test.go b/services/gateway-service/internal/transport/http/response_test.go
index 5207b0d6..54c19e7b 100644
--- a/services/gateway-service/internal/transport/http/response_test.go
+++ b/services/gateway-service/internal/transport/http/response_test.go
@@ -8013,6 +8013,22 @@ func TestCompleteOnboardingAllowsIncompleteProfileAndUsesAuthenticatedUserID(t *
 	}
 }
 
+func TestCompleteOnboardingReturnsInvalidInviteCodeMessage(t *testing.T) {
+	profileClient := &fakeUserProfileClient{
+		completeErr: xerr.ToGRPCError(xerr.New(xerr.InvalidInviteCode, "invalid invite code")),
+	}
+	router := NewHandlerWithClients(&fakeRoomClient{}, nil, nil, profileClient).Routes(auth.NewVerifier("secret"))
+	body := []byte(`{"username":"hy","avatar":"https://cdn.example/a.png","gender":"male","country":"SG","invite_code":"BADCODE"}`)
+	request := httptest.NewRequest(http.MethodPost, "/api/v1/users/me/onboarding/complete", bytes.NewReader(body))
+	request.Header.Set("Authorization", "Bearer "+signGatewayTokenWithProfile(t, "secret", 42, false))
+	request.Header.Set("X-Request-ID", "req-onboarding-invalid-invite")
+	recorder := httptest.NewRecorder()
+
+	router.ServeHTTP(recorder, request)
+
+	assertEnvelopeMessage(t, recorder, http.StatusBadRequest, string(xerr.InvalidInviteCode), "invalid invite code", "req-onboarding-invalid-invite")
+}
+
 func TestProfileMutationEndpointsRequireCompletedProfileToken(t *testing.T) {
 	tests := []struct {
 		name string