diff --git a/backend/internal/services/admin.go b/backend/internal/services/admin.go
index 97e12fd..fa2625e 100644
--- a/backend/internal/services/admin.go
+++ b/backend/internal/services/admin.go
@@ -1,6 +1,7 @@
 package services
 
 import (
+	"Noooste/garage-ui/internal/apierr"
 	"Noooste/garage-ui/internal/config"
 	"Noooste/garage-ui/internal/models"
 	"Noooste/garage-ui/pkg/utils"
@@ -63,13 +64,14 @@ func (s *GarageAdminService) doRequest(ctx context.Context, method, path string,
 	return resp, nil
 }
 
-// decodeResponse decodes a JSON response into the target structure
+// decodeResponse decodes a JSON response into the target structure. Non-2xx
+// responses are converted to *apierr.UpstreamError (Source="garage") so the
+// handler layer can map them to the correct API error code and HTTP status.
 func decodeResponse(resp *azuretls.Response, target interface{}) error {
 	defer resp.RawBody.Close()
 
-	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
-		bodyBytes, _ := io.ReadAll(resp.RawBody)
-		return fmt.Errorf("API returned status %d: %s", resp.StatusCode, string(bodyBytes))
+	if err := apierr.ParseGarage(resp); err != nil {
+		return err
 	}
 
 	if target != nil {
@@ -77,7 +79,6 @@ func decodeResponse(resp *azuretls.Response, target interface{}) error {
 			return fmt.Errorf("failed to decode response: %w", err)
 		}
 	}
-
 	return nil
 }
 
diff --git a/backend/internal/services/admin_test.go b/backend/internal/services/admin_test.go
index f252cfe..4f247b1 100644
--- a/backend/internal/services/admin_test.go
+++ b/backend/internal/services/admin_test.go
@@ -3,6 +3,7 @@ package services
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"io"
 	"net"
 	"net/http"
@@ -11,6 +12,7 @@ import (
 	"testing"
 	"time"
 
+	"Noooste/garage-ui/internal/apierr"
 	"Noooste/garage-ui/internal/config"
 	"Noooste/garage-ui/internal/models"
 )
@@ -103,8 +105,12 @@ func TestHealthCheck_Non2xxReturnsError(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected error for 503, got nil")
 	}
-	if !strings.Contains(err.Error(), "503") {
-		t.Errorf("error should mention status code, got %v", err)
+	var ue *apierr.UpstreamError
+	if !errors.As(err, &ue) {
+		t.Fatalf("expected *apierr.UpstreamError, got %T (%v)", err, err)
+	}
+	if ue.HTTPStatus != http.StatusServiceUnavailable {
+		t.Errorf("HTTPStatus = %d, want %d", ue.HTTPStatus, http.StatusServiceUnavailable)
 	}
 }
 
@@ -509,8 +515,15 @@ func TestDoRequest_Non2xxBodyEchoedInError(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected error for 400, got nil")
 	}
-	if !strings.Contains(err.Error(), "400") || !strings.Contains(err.Error(), "bad request") {
-		t.Errorf("error %v should contain 400 and the response body", err)
+	var ue *apierr.UpstreamError
+	if !errors.As(err, &ue) {
+		t.Fatalf("expected *apierr.UpstreamError, got %T (%v)", err, err)
+	}
+	if ue.HTTPStatus != http.StatusBadRequest {
+		t.Errorf("HTTPStatus = %d, want %d", ue.HTTPStatus, http.StatusBadRequest)
+	}
+	if !strings.Contains(ue.Message, "bad request") {
+		t.Errorf("Message = %q, want it to contain the response body", ue.Message)
 	}
 }