diff --git a/radicale/web/internal_data/js/api/api.js b/radicale/web/internal_data/js/api/api.js
index 4754d61f..d061523f 100644
--- a/radicale/web/internal_data/js/api/api.js
+++ b/radicale/web/internal_data/js/api/api.js
@@ -22,7 +22,7 @@
 import { COLOR_RE, ROOT_PATH, SERVER } from "../constants.js";
 import { Collection, CollectionType } from "../models/collection.js";
 import { escape_xml } from "../utils/misc.js";
-
+import { to_error_message } from "./common.js";
 
 /**
  * Find the principal collection.
@@ -56,7 +56,7 @@ export function get_principal(user, password, callback) {
                 callback(null, "Internal error");
             }
         } else {
-            callback(null, request.status + " " + request.statusText);
+            callback(null, to_error_message(request));
         }
     };
     request.send('<?xml version="1.0" encoding="utf-8" ?>' +
@@ -163,7 +163,7 @@ export function get_collections(user, password, collection, callback) {
             });
             callback(collections, null);
         } else {
-            callback(null, request.status + " " + request.statusText);
+            callback(null, to_error_message(request));
         }
     };
     request.send('<?xml version="1.0" encoding="utf-8" ?>' +
@@ -210,7 +210,7 @@ export function upload_collection(user, password, collection_href, file, callbac
         if (200 <= request.status && request.status < 300) {
             callback(null);
         } else {
-            callback(request.status + " " + request.statusText);
+            callback(to_error_message(request));
         }
     };
     request.setRequestHeader("If-None-Match", "*");
@@ -235,7 +235,7 @@ export function delete_collection(user, password, collection, callback) {
         if (200 <= request.status && request.status < 300) {
             callback(null);
         } else {
-            callback(request.status + " " + request.statusText);
+            callback(to_error_message(request));
         }
     };
     request.send();
@@ -260,7 +260,7 @@ function create_edit_collection(user, password, collection, create, callback) {
         if (200 <= request.status && request.status < 300) {
             callback(null);
         } else {
-            callback(request.status + " " + request.statusText);
+            callback(to_error_message(request));
         }
     };
     let displayname = escape_xml(collection.displayname);
diff --git a/radicale/web/internal_data/js/api/common.js b/radicale/web/internal_data/js/api/common.js
new file mode 100644
index 00000000..c69637e9
--- /dev/null
+++ b/radicale/web/internal_data/js/api/common.js
@@ -0,0 +1,33 @@
+/**
+ * This file is part of Radicale Server - Calendar Server
+ * Copyright © 2017-2024 Unrud <unrud@outlook.com>
+ * Copyright © 2023-2024 Matthew Hana <matthew.hana@gmail.com>
+ * Copyright © 2024-2025 Peter Bieringer <pb@bieringer.de>
+ * Copyright © 2026-2026 Max Berger <max@berger.name>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * @param {XMLHttpRequest} request
+ * @returns {string}
+ */
+export function to_error_message(request) {
+    let have_status_text = (request.statusText != null && request.statusText != undefined && request.statusText != '')
+    if ((request.status == 0) && (!have_status_text)) {
+        return "Could not connect to server";
+    }
+
+    return request.status + " " + request.statusText;
+}
\ No newline at end of file
diff --git a/radicale/web/internal_data/js/api/sharing.js b/radicale/web/internal_data/js/api/sharing.js
index be118039..1d3feedc 100644
--- a/radicale/web/internal_data/js/api/sharing.js
+++ b/radicale/web/internal_data/js/api/sharing.js
@@ -18,6 +18,7 @@
 
 import { ROOT_PATH, SERVER } from "../constants.js";
 import { CollectionType } from "../models/collection.js";
+import { to_error_message } from "./common.js";
 
 /**
  * @typedef {Object} SharingFeatures
@@ -79,9 +80,9 @@ function call_sharing_api(
             }
         } else {
             if (on_error) {
-                on_error(request.status + " " + request.statusText);
+                on_error(to_error_message(request));
             } else {
-                console.error(request.status + " " + request.statusText);
+                console.error(to_error_message(request));
             }
         }
     };