diff --git a/Core/Assets/JS/ListFilterAutocomplete.js b/Core/Assets/JS/ListFilterAutocomplete.js
index 1d0cc2dd7e..137022e6fa 100644
--- a/Core/Assets/JS/ListFilterAutocomplete.js
+++ b/Core/Assets/JS/ListFilterAutocomplete.js
@@ -16,6 +16,10 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
+function listFilterAutocompleteMsg(key) {
+    return (typeof i18n !== 'undefined' && i18n[key]) ? i18n[key] : key;
+}
+
 function listFilterAutocompleteGetData(formId, formData, term) {
     var rawForm = $("form[id=" + formId + "]").serializeArray();
     $.each(rawForm, function (i, input) {
@@ -44,18 +48,42 @@ $(document).ready(function () {
                     data: listFilterAutocompleteGetData(formId, data, request.term),
                     dataType: "json",
                     success: function (results) {
-                        var values = [];
-                        results.forEach(function (element) {
-                            if (element.key === null || element.key === element.value) {
-                                values.push(element);
-                            } else {
-                                values.push({key: element.key, value: element.key + " | " + element.value});
+                        try {
+                            if (!Array.isArray(results)) {
+                                throw new Error('response is not an array');
                             }
-                        });
-                        response(values);
+                            var values = [];
+                            results.forEach(function (element) {
+                                if (!element || element.key === undefined || element.value === undefined || element.value === null) {
+                                    console.warn('filter-autocomplete: invalid element ignored', element);
+                                    return;
+                                }
+                                if (element.key === null || element.key === element.value) {
+                                    values.push(element);
+                                } else {
+                                    values.push({key: element.key, value: element.key + " | " + element.value});
+                                }
+                            });
+                            response(values);
+                        } catch (e) {
+                            console.error('filter-autocomplete: invalid JSON response', e);
+                            alert(listFilterAutocompleteMsg('autocomplete-error-invalid-response'));
+                            response([]);
+                        }
                     },
-                    error: function (msg) {
-                        alert(msg.status + " " + msg.responseText);
+                    error: function (msg, textStatus, errorThrown) {
+                        console.error('filter-autocomplete AJAX error | status:', msg.status, '| textStatus:', textStatus, '| errorThrown:', errorThrown);
+                        console.error('filter-autocomplete responseText:', msg.responseText);
+                        if (msg.status === 0) {
+                            alert(listFilterAutocompleteMsg('autocomplete-error-network'));
+                        } else if (msg.status === 400) {
+                            alert(listFilterAutocompleteMsg('autocomplete-error-bad-request'));
+                        } else if (msg.status >= 500) {
+                            alert(listFilterAutocompleteMsg('autocomplete-error-server'));
+                        } else {
+                            alert(listFilterAutocompleteMsg('autocomplete-error-generic'));
+                        }
+                        response([]);
                     }
                 });
             },
diff --git a/Core/Assets/JS/WidgetAutocomplete.js b/Core/Assets/JS/WidgetAutocomplete.js
index 7f1555dcfe..450f1eb220 100644
--- a/Core/Assets/JS/WidgetAutocomplete.js
+++ b/Core/Assets/JS/WidgetAutocomplete.js
@@ -16,6 +16,10 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
+function widgetAutocompleteMsg(key) {
+    return (typeof i18n !== 'undefined' && i18n[key]) ? i18n[key] : key;
+}
+
 function widgetAutocompleteGetData(formId, formData, term) {
     var rawForm = $("form[id=" + formId + "]").serializeArray();
     $.each(rawForm, function (i, input) {
@@ -45,23 +49,42 @@ $(document).ready(function () {
                     data: widgetAutocompleteGetData(formId, data, request.term),
                     dataType: "json",
                     success: function (results) {
-                        var values = [];
-                        results.forEach(function (element) {
-                            if (element.key === null || element.key === element.value) {
-                                values.push(element);
-                            } else {
-                                values.push({key: element.key, value: element.key + " | " + element.value});
+                        try {
+                            if (!Array.isArray(results)) {
+                                throw new Error('response is not an array');
                             }
-                        });
-                        response(values);
+                            var values = [];
+                            results.forEach(function (element) {
+                                if (!element || element.key === undefined || element.value === undefined || element.value === null) {
+                                    console.warn('widget-autocomplete: invalid element ignored', element);
+                                    return;
+                                }
+                                if (element.key === null || element.key === element.value) {
+                                    values.push(element);
+                                } else {
+                                    values.push({key: element.key, value: element.key + " | " + element.value});
+                                }
+                            });
+                            response(values);
+                        } catch (e) {
+                            console.error('widget-autocomplete: invalid JSON response', e);
+                            alert(widgetAutocompleteMsg('autocomplete-error-invalid-response'));
+                            response([]);
+                        }
                     },
                     error: function (msg, textStatus, errorThrown) {
-                        console.log('widget-autocomplete AJAX ERROR');
-                        console.log('status:', msg.status);
-                        console.log('textStatus:', textStatus);
-                        console.log('errorThrown:', errorThrown);
-                        console.log('responseText:', msg.responseText);
-                        alert(msg.status + " " + msg.responseText);
+                        console.error('widget-autocomplete AJAX error | status:', msg.status, '| textStatus:', textStatus, '| errorThrown:', errorThrown);
+                        console.error('widget-autocomplete responseText:', msg.responseText);
+                        if (msg.status === 0) {
+                            alert(widgetAutocompleteMsg('autocomplete-error-network'));
+                        } else if (msg.status === 400) {
+                            alert(widgetAutocompleteMsg('autocomplete-error-bad-request'));
+                        } else if (msg.status >= 500) {
+                            alert(widgetAutocompleteMsg('autocomplete-error-server'));
+                        } else {
+                            alert(widgetAutocompleteMsg('autocomplete-error-generic'));
+                        }
+                        response([]);
                     }
                 });
             },
diff --git a/Core/Translation/en_EN.json b/Core/Translation/en_EN.json
index f8be43c908..f818dfe2bc 100644
--- a/Core/Translation/en_EN.json
+++ b/Core/Translation/en_EN.json
@@ -150,6 +150,11 @@
     "authentication": "Authentication",
     "auto": "Auto",
     "auto-apply-to": "Automatically apply to",
+    "autocomplete-error-bad-request": "Bad request to the server. Please reload the page.",
+    "autocomplete-error-generic": "An error occurred while loading options. Please try again.",
+    "autocomplete-error-invalid-response": "The server response is not valid. Please reload the page.",
+    "autocomplete-error-network": "Could not connect to the server. Please check your internet connection.",
+    "autocomplete-error-server": "Internal server error. Please try again.",
     "automatic": "Automatic",
     "available": "Available",
     "average": "Average",
diff --git a/Core/Translation/es_ES.json b/Core/Translation/es_ES.json
index a4a84da986..c7cff166eb 100644
--- a/Core/Translation/es_ES.json
+++ b/Core/Translation/es_ES.json
@@ -150,6 +150,11 @@
     "authentication": "Autenticación",
     "auto": "Auto",
     "auto-apply-to": "Aplicar automáticamente a",
+    "autocomplete-error-bad-request": "Solicitud incorrecta al servidor. Por favor, recarga la página.",
+    "autocomplete-error-generic": "Ha ocurrido un error al cargar las opciones. Por favor, inténtalo de nuevo.",
+    "autocomplete-error-invalid-response": "La respuesta del servidor no es válida. Por favor, recarga la página.",
+    "autocomplete-error-network": "No se ha podido conectar con el servidor. Comprueba tu conexión a internet.",
+    "autocomplete-error-server": "Error interno del servidor. Por favor, inténtalo de nuevo.",
     "automatic": "Automático",
     "available": "Disponible",
     "average": "Media",
diff --git a/Core/View/Master/MenuTemplate.html.twig b/Core/View/Master/MenuTemplate.html.twig
index 6c632fc285..c981e4c3fd 100644
--- a/Core/View/Master/MenuTemplate.html.twig
+++ b/Core/View/Master/MenuTemplate.html.twig
@@ -64,6 +64,16 @@
         <script src="{{ asset('node_modules/@fortawesome/fontawesome-free/js/all.min.js') }}?v=6"></script>
         <script src="{{ asset('Dinamic/Assets/JS/Custom.js') }}?v={{ 'now' | date('ymd') }}"></script>
     {% endblock %}
+    {# Global translations for JS #}
+    <script>
+        var i18n = {
+            "autocomplete-error-network": "{{ trans('autocomplete-error-network') }}",
+            "autocomplete-error-bad-request": "{{ trans('autocomplete-error-bad-request') }}",
+            "autocomplete-error-server": "{{ trans('autocomplete-error-server') }}",
+            "autocomplete-error-generic": "{{ trans('autocomplete-error-generic') }}",
+            "autocomplete-error-invalid-response": "{{ trans('autocomplete-error-invalid-response') }}"
+        };
+    </script>
     {# Adds custom JS assets #}
     {% for js in assetManager.get('js') %}
         <script src="{{ js }}"></script>