diff --git a/pkg/handler/resources.go b/pkg/handler/resources.go
index 2e70f2e73..0272d3ecf 100644
--- a/pkg/handler/resources.go
+++ b/pkg/handler/resources.go
@@ -34,7 +34,7 @@ func (h *Handlers) GetClusters(ctx context.Context) func(w http.ResponseWriter,
 		// Fetch and merge values for K8S_ClusterName
 		values, code, err := h.getLabelValues(ctx, clients, fields.Cluster)
 		if err != nil {
-			writeError(w, code, "Error while fetching label cluster values from Loki: "+err.Error())
+			writeError(w, code, err.Error())
 			return
 		}
 
@@ -65,14 +65,14 @@ func (h *Handlers) GetZones(ctx context.Context) func(w http.ResponseWriter, r *
 		// Fetch and merge values for SrcK8S_Zone and DstK8S_Zone
 		values1, code, err := h.getLabelValues(ctx, clients, fields.SrcZone)
 		if err != nil {
-			writeError(w, code, "Error while fetching label source zone values from Loki: "+err.Error())
+			writeError(w, code, err.Error())
 			return
 		}
 		values = append(values, values1...)
 
 		values2, code, err := h.getLabelValues(ctx, clients, fields.DstZone)
 		if err != nil {
-			writeError(w, code, "Error while fetching label destination zone values from Loki: "+err.Error())
+			writeError(w, code, err.Error())
 			return
 		}
 		values = append(values, values2...)
@@ -104,14 +104,14 @@ func (h *Handlers) GetNamespaces(ctx context.Context) func(w http.ResponseWriter
 		// Fetch and merge values for SrcK8S_Namespace and DstK8S_Namespace
 		values1, code, err := h.getLabelValues(ctx, clients, fields.SrcNamespace)
 		if err != nil {
-			writeError(w, code, "Error while fetching label source namespace values from Loki: "+err.Error())
+			writeError(w, code, err.Error())
 			return
 		}
 		values = append(values, values1...)
 
 		values2, code, err := h.getLabelValues(ctx, clients, fields.DstNamespace)
 		if err != nil {
-			writeError(w, code, "Error while fetching label destination namespace values from Loki: "+err.Error())
+			writeError(w, code, err.Error())
 			return
 		}
 		values = append(values, values2...)
@@ -123,10 +123,27 @@ func (h *Handlers) GetNamespaces(ctx context.Context) func(w http.ResponseWriter
 
 func (h *Handlers) getLabelValues(ctx context.Context, cl clients, label string) ([]string, int, error) {
 	if h.PromInventory != nil && h.PromInventory.LabelExists(label) {
-		return prometheus.GetLabelValues(ctx, cl.promAdmin, label, nil)
+		resp, code, err := prometheus.GetLabelValues(ctx, cl.promAdmin, label, nil)
+		if err != nil {
+			if code == http.StatusUnauthorized || code == http.StatusForbidden {
+				// In case this was a prometheus 401 / 403 error, the query is repeated with Loki
+				// This is because multi-tenancy is currently not managed for prom datasource, hence such queries have to go with Loki
+				// Unfortunately we don't know a safe and generic way to pre-flight check if the user will be authorized
+				hlog.Info("Retrying with Loki...")
+				// continuing with loki below
+			} else {
+				return nil, code, fmt.Errorf("error while fetching label %s values from Prometheus: %w", label, err)
+			}
+		} else {
+			return resp, code, nil
+		}
 	}
 	if h.Cfg.IsLokiEnabled() {
-		return getLokiLabelValues(h.Cfg.Loki.URL, cl.loki, label)
+		resp, code, err := getLokiLabelValues(h.Cfg.Loki.URL, cl.loki, label)
+		if err != nil {
+			return nil, code, fmt.Errorf("error while fetching label %s values from Loki: %w", label, err)
+		}
+		return resp, code, nil
 	}
 	// Loki disabled AND label not managed in metrics => send an error
 	return nil, http.StatusBadRequest, fmt.Errorf("label %s not found in Prometheus metrics", label)
@@ -186,7 +203,7 @@ func (h *Handlers) getNamesForPrefix(ctx context.Context, cl clients, prefix, ki
 		searchField = prefix + fields.Name
 	}
 
-	if h.Cfg.IsPromEnabled() {
+	if h.Cfg.IsPromEnabled() && h.PromInventory.LabelExists(searchField) {
 		// Label match query (any metric)
 		q := prometheus.QueryFilters("", filts)
 		return prometheus.GetLabelValues(ctx, cl.promAdmin, searchField, []string{q})
diff --git a/pkg/prometheus/client.go b/pkg/prometheus/client.go
index 787430743..843590ad2 100644
--- a/pkg/prometheus/client.go
+++ b/pkg/prometheus/client.go
@@ -79,15 +79,7 @@ func executeQueryRange(ctx context.Context, cl api.Client, q *Query) (pmod.Value
 	}
 	if err != nil {
 		log.Tracef("Error:\n%v", err)
-		code = http.StatusServiceUnavailable
-		var promError *v1.Error
-		if errors.As(err, &promError) {
-			if promError.Type == v1.ErrClient && strings.Contains(promError.Msg, "401") {
-				code = http.StatusUnauthorized
-			} else if promError.Type == v1.ErrClient && strings.Contains(promError.Msg, "403") {
-				code = http.StatusForbidden
-			}
-		}
+		code = translateErrorCode(err)
 		return nil, code, fmt.Errorf("error from Prometheus query: %w", err)
 	}
 
@@ -125,12 +117,13 @@ func GetLabelValues(ctx context.Context, cl api.Client, label string, match []st
 	log.Debugf("GetLabelValues: %s", label)
 	v1api := v1.NewAPI(cl)
 	result, warnings, err := v1api.LabelValues(ctx, label, match, time.Now().Add(-3*time.Hour), time.Now())
-	if err != nil {
-		return nil, http.StatusServiceUnavailable, err
-	}
 	if len(warnings) > 0 {
 		log.Infof("GetLabelValues warnings: %v", warnings)
 	}
+	if err != nil {
+		code := translateErrorCode(err)
+		return nil, code, fmt.Errorf("could not get label values: %w", err)
+	}
 	log.Tracef("Result:\n%v", result)
 	var asStrings []string
 	for _, s := range result {
@@ -138,3 +131,15 @@ func GetLabelValues(ctx context.Context, cl api.Client, label string, match []st
 	}
 	return asStrings, http.StatusOK, nil
 }
+
+func translateErrorCode(err error) int {
+	var promError *v1.Error
+	if errors.As(err, &promError) {
+		if promError.Type == v1.ErrClient && strings.Contains(promError.Msg, "401") {
+			return http.StatusUnauthorized
+		} else if promError.Type == v1.ErrClient && strings.Contains(promError.Msg, "403") {
+			return http.StatusForbidden
+		}
+	}
+	return http.StatusServiceUnavailable
+}
diff --git a/web/src/components/toolbar/filters/autocomplete-filter.tsx b/web/src/components/toolbar/filters/autocomplete-filter.tsx
index adb578159..f4ce29151 100644
--- a/web/src/components/toolbar/filters/autocomplete-filter.tsx
+++ b/web/src/components/toolbar/filters/autocomplete-filter.tsx
@@ -86,9 +86,7 @@ export const AutocompleteFilter: React.FC<AutocompleteFilterProps> = ({
       setCurrentValue(newValue);
       filterDefinition
         .getOptions(newValue)
-        .then(opts => {
-          setOptions(opts);
-        })
+        .then(setOptions)
         .catch(err => {
           const errorMessage = getHTTPErrorDetails(err);
           setMessageWithDelay(errorMessage);
diff --git a/web/src/model/filters.ts b/web/src/model/filters.ts
index f652b4c35..a3a20639c 100644
--- a/web/src/model/filters.ts
+++ b/web/src/model/filters.ts
@@ -92,10 +92,16 @@ export interface FilterOption {
 }
 
 export const createFilterValue = (def: FilterDefinition, value: string): Promise<FilterValue> => {
-  return def.getOptions(value).then(opts => {
-    const option = opts.find(opt => opt.name === value || opt.value === value);
-    return option ? { v: option.value, display: option.name } : { v: value };
-  });
+  return def
+    .getOptions(value)
+    .then(opts => {
+      const option = opts.find(opt => opt.name === value || opt.value === value);
+      return option ? { v: option.value, display: option.name } : { v: value };
+    })
+    .catch(_ => {
+      // In case of error, still create the minimal possible FilterValue
+      return { v: value };
+    });
 };
 
 export const hasEnabledFilterValues = (filter: Filter) => {