diff --git a/radicale/web/internal_data/index.html b/radicale/web/internal_data/index.html
index d77a9711..3afc37de 100644
--- a/radicale/web/internal_data/index.html
+++ b/radicale/web/internal_data/index.html
@@ -200,6 +200,7 @@
       <form>
         <button type="button" class="green" data-name="cancel">Close</button>
       </form>
+      <span class="error hidden" data-name="error"></span>
     </section>
 
     <section id="newshare" class="container hidden">
@@ -233,6 +234,7 @@
         <button type="submit" class="green" data-name="submit">Create</button>
         <button type="button" class="red" data-name="cancel">Cancel</button>
       </form>
+      <span class="error hidden" data-name="error"></span>
     </section>
 
     <section id="createcollectionscene" class="container hidden">
@@ -312,4 +314,4 @@
   </main>
 </body>
 
-</html>
+</html>
\ No newline at end of file
diff --git a/radicale/web/internal_data/js/api/api.js b/radicale/web/internal_data/js/api/api.js
index 81bf5059..e493eedd 100644
--- a/radicale/web/internal_data/js/api/api.js
+++ b/radicale/web/internal_data/js/api/api.js
@@ -464,7 +464,7 @@ export function discover_server_features(user, password, callback) {
  * @param {string} user
  * @param {string} password
  * @param {Collection} collection
- * @param {function(Array<Share>):void} callback
+ * @param {function(Array<Share>, ?string):void} callback
  */
 export function reload_sharing_list(user, password, collection, callback) {
     call_sharing_api(
@@ -474,8 +474,12 @@ export function reload_sharing_list(user, password, collection, callback) {
         { PathMapped: collection.href },
         function (response) {
             let parsed = JSON.parse(response);
-            callback(parsed["Content"] || []);
+            callback(parsed["Content"] || [], null);
         },
+        null, // on_not_found
+        function (error) {
+            callback([], error);
+        }
     );
 }
 
@@ -487,7 +491,7 @@ export function reload_sharing_list(user, password, collection, callback) {
  * @param {boolean} enabled
  * @param {boolean} hidden
  * @param {string} properties
- * @param {function():void} callback
+ * @param {function(?string):void} callback
  */
 export function add_share_by_token(
     user,
@@ -513,11 +517,15 @@ export function add_share_by_token(
         function (response) {
             let json_response = JSON.parse(response);
             if (json_response["Status"] !== "success") {
-                console.error("Failed to create share token: " + (json_response["Status"] || "Unknown error"));
+                callback(json_response["Status"] || "Unknown error");
             } else {
-                callback();
+                callback(null);
             }
         },
+        null,
+        function (error) {
+            callback(error);
+        }
     );
 }
 
@@ -531,7 +539,7 @@ export function add_share_by_token(
  * @param {string} properties
  * @param {string} share_user
  * @param {string} href
- * @param {function():void} callback
+ * @param {function(?string):void} callback
  */
 export function add_share_by_map(
     user,
@@ -561,11 +569,15 @@ export function add_share_by_map(
         function (response) {
             let json_response = JSON.parse(response);
             if (json_response["Status"] !== "success") {
-                console.error("Failed to create share map: " + (json_response["Status"] || "Unknown error"));
+                callback(json_response["Status"] || "Unknown error");
             } else {
-                callback();
+                callback(null);
             }
         },
+        null,
+        function (error) {
+            callback(error);
+        }
     );
 }
 
@@ -573,7 +585,7 @@ export function add_share_by_map(
  * @param {string} user
  * @param {string} password
  * @param {string} token
- * @param {function():void} callback
+ * @param {function(?string):void} callback
  */
 export function delete_share_by_token(
     user,
@@ -589,11 +601,15 @@ export function delete_share_by_token(
         function (response) {
             let json_response = JSON.parse(response);
             if (json_response["Status"] !== "success") {
-                console.error("Failed to create delete token " + token + ": " + (json_response["Status"] || "Unknown error"));
+                callback(json_response["Status"] || "Unknown error");
             } else {
-                callback();
+                callback(null);
             }
         },
+        null,
+        function (error) {
+            callback(error);
+        }
     );
 }
 
@@ -601,7 +617,7 @@ export function delete_share_by_token(
  * @param {string} user
  * @param {string} password
  * @param {string} pathortoken
- * @param {function():void} callback
+ * @param {function(?string):void} callback
  */
 export function delete_share_by_map(
     user,
@@ -617,10 +633,14 @@ export function delete_share_by_map(
         function (response) {
             let json_response = JSON.parse(response);
             if (json_response["Status"] !== "success") {
-                console.error("Failed to delete map " + pathortoken + ": " + (json_response["Status"] || "Unknown error"));
+                callback(json_response["Status"] || "Unknown error");
             } else {
-                callback();
+                callback(null);
             }
         },
+        null,
+        function (error) {
+            callback(error);
+        }
     );
 }
diff --git a/radicale/web/internal_data/js/scenes/NewShareScene.js b/radicale/web/internal_data/js/scenes/NewShareScene.js
index 6ae47167..9f9aedaa 100644
--- a/radicale/web/internal_data/js/scenes/NewShareScene.js
+++ b/radicale/web/internal_data/js/scenes/NewShareScene.js
@@ -20,7 +20,9 @@
  */
 
 import { add_share_by_map, add_share_by_token } from "../api/api.js";
-import { onCleanHREFinput } from "../utils/misc.js";
+import { ErrorHandler } from "../utils/error.js";
+import { FormValidator, validate_href, validate_non_empty } from "../utils/form_validator.js";
+import { onCleanHREFinput, random_uuid } from "../utils/misc.js";
 import { Scene, pop_scene, scene_stack } from "./scene_manager.js";
 
 /**
@@ -45,8 +47,15 @@ export class NewShareScene {
         let permissions_ro_radio = /** @type {HTMLInputElement} */ (document.getElementById("newshare_attr_permissions_ro"));
         let permissions_rw_radio = /** @type {HTMLInputElement} */ (document.getElementById("newshare_attr_permissions_rw"));
         /** @type {HTMLInputElement} */ let properties_input = html_scene.querySelector("[data-name=properties]");
+        /** @type {HTMLElement} */ let error_form = html_scene.querySelector("[data-name=error]");
         /** @type {HTMLElement} */ let cancel_btn = html_scene.querySelector("[data-name=cancel]");
 
+        let errorHandler = new ErrorHandler(error_form);
+        let map_validator = new FormValidator(errorHandler);
+
+        map_validator.addValidator(shareuser_input, validate_non_empty(shareuser_input, "Share User"));
+        map_validator.addValidator(sharehref_input, validate_href(sharehref_input, "Share Href"));
+
         sharehref_input.addEventListener("input", onCleanHREFinput);
 
         /** @type {?number} */ let scene_index = null;
@@ -65,16 +74,26 @@ export class NewShareScene {
 
         function onsubmit() {
             try {
+                if (shareType === "map") {
+                    if (!map_validator.validate()) {
+                        return false;
+                    }
+                }
                 let enabled = enabled_checkbox.checked;
                 let hidden = hidden_checkbox.checked;
                 let permissions = permissions_rw_radio.checked ? "rw" : "r";
                 let properties = properties_input.value;
 
-                let callback = function () {
-                    if (scene_index !== null) {
-                        pop_scene(scene_index - 1);
+                let callback = function (/** @type {string} */ error) {
+                    if (scene_index === null) {
+                        return;
+                    }
+                    if (error) {
+                        errorHandler.setError(error);
+                    } else {
+                        pop_scene(scene_index - 1);
+                        if (onclose) onclose();
                     }
-                    if (onclose) onclose();
                 };
 
                 if (shareType === "map") {
@@ -97,19 +116,22 @@ export class NewShareScene {
             cancel_btn.onclick = oncancel;
             form.onsubmit = onsubmit;
 
-            if (shareType === "map") {
-                sharemapfields.classList.remove("hidden");
-            } else {
-                sharemapfields.classList.add("hidden");
-            }
 
             shareuser_input.value = "";
-            sharehref_input.value = "";
             enabled_checkbox.checked = true;
             hidden_checkbox.checked = false;
             permissions_ro_radio.checked = true;
             permissions_rw_radio.checked = false;
             properties_input.value = "";
+            if (shareType === "map") {
+                sharehref_input.value = random_uuid();
+                sharemapfields.classList.remove("hidden");
+                map_validator.validate();
+            } else {
+                sharehref_input.value = "";
+                sharemapfields.classList.add("hidden");
+                errorHandler.clearError();
+            }
         };
 
         this.hide = function () {
diff --git a/radicale/web/internal_data/js/scenes/ShareCollectionScene.js b/radicale/web/internal_data/js/scenes/ShareCollectionScene.js
index 0b21c973..d5e28fa8 100644
--- a/radicale/web/internal_data/js/scenes/ShareCollectionScene.js
+++ b/radicale/web/internal_data/js/scenes/ShareCollectionScene.js
@@ -26,6 +26,7 @@ import {
   server_features,
 } from "../api/api.js";
 import { Collection } from "../models/collection.js";
+import { ErrorHandler } from "../utils/error.js";
 import { NewShareScene } from "./NewShareScene.js";
 import { Scene, pop_scene, push_scene, scene_stack } from "./scene_manager.js";
 
@@ -56,8 +57,11 @@ export class ShareCollectionScene {
     /** @type {HTMLElement} */ let share_by_map_div = html_scene.querySelector(
       "div[data-name=sharebymap]"
     );
+    /** @type {HTMLElement} */ let error_form = html_scene.querySelector("[data-name=error]");
 
-        /** @type {HTMLElement} */ let title = html_scene.querySelector("[data-name=title]");
+    let errorHandler = new ErrorHandler(error_form);
+
+    /** @type {HTMLElement} */ let title = html_scene.querySelector("[data-name=title]");
 
     function oncancel() {
       try {
@@ -70,14 +74,14 @@ export class ShareCollectionScene {
 
     function onsharebytoken() {
       let new_share_scene = new NewShareScene(user, password, collection.href, "token", function () {
-        update_share_list(user, password, collection);
+        update_share_list(user, password, collection, errorHandler);
       });
       push_scene(new_share_scene, false);
     }
 
     function onsharebymap() {
       let new_share_scene = new NewShareScene(user, password, collection.href, "map", function () {
-        update_share_list(user, password, collection);
+        update_share_list(user, password, collection, errorHandler);
       });
       push_scene(new_share_scene, false);
     }
@@ -118,7 +122,7 @@ export class ShareCollectionScene {
       }
 
       title.textContent = collection.displayname || collection.href;
-      update_share_list(user, password, collection);
+      update_share_list(user, password, collection, errorHandler);
     };
     this.hide = function () {
       html_scene.classList.add("hidden");
@@ -134,8 +138,9 @@ export class ShareCollectionScene {
  * @param {string} user
  * @param {string} password
  * @param {Collection} collection
+ * @param {ErrorHandler} errorHandler
  */
-function update_share_list(user, password, collection) {
+function update_share_list(user, password, collection, errorHandler) {
   let share_rows = document.querySelectorAll(
     "[data-name=sharetokenrowtemplate], [data-name=sharemaprowtemplate]",
   );
@@ -145,8 +150,12 @@ function update_share_list(user, password, collection) {
     }
   });
 
-  reload_sharing_list(user, password, collection, function (shares) {
-    add_share_rows(user, password, collection, shares);
+  reload_sharing_list(user, password, collection, function (shares, error) {
+    if (error) {
+      errorHandler.setError(error);
+    } else {
+      add_share_rows(user, password, collection, shares, errorHandler);
+    }
   });
 }
 
@@ -158,9 +167,10 @@ function update_share_list(user, password, collection) {
  * @param {import('../api/api.js').Share} share 
  * @param {HTMLElement} template 
  * @param {string} delete_label 
- * @param {function(string, string, string, function():void):void} delete_action 
+ * @param {function(string, string, string, function(?string):void):void} delete_action 
+ * @param {ErrorHandler} errorHandler
  */
-function add_share_row_node(user, password, collection, share, template, delete_label, delete_action) {
+function add_share_row_node(user, password, collection, share, template, delete_label, delete_action, errorHandler) {
   let pathortoken = share["PathOrToken"] || "";
   let node = /** @type {HTMLElement} */ (template.cloneNode(true));
   node.classList.remove("hidden");
@@ -192,8 +202,12 @@ function add_share_row_node(user, password, collection, share, template, delete_
       user,
       password,
       pathortoken,
-      function () {
-        update_share_list(user, password, collection);
+      function (error) {
+        if (error) {
+          errorHandler.setError(error);
+        } else {
+          update_share_list(user, password, collection, errorHandler);
+        }
       },
     );
   };
@@ -206,8 +220,9 @@ function add_share_row_node(user, password, collection, share, template, delete_
  * @param {string} password 
  * @param {Collection} collection 
  * @param {Array<import('../api/api.js').Share>} shares 
+ * @param {ErrorHandler} errorHandler
  */
-function add_share_rows(user, password, collection, shares) {
+function add_share_rows(user, password, collection, shares, errorHandler) {
   /** @type {HTMLElement} */ let token_template = document.querySelector("[data-name=sharetokenrowtemplate]");
   /** @type {HTMLElement} */ let map_template = document.querySelector("[data-name=sharemaprowtemplate]");
   shares.forEach(function (share) {
@@ -218,9 +233,9 @@ function add_share_rows(user, password, collection, shares) {
       collection.href.includes(pathortoken)
     ) {
       if (share["ShareType"] === "token") {
-        add_share_row_node(user, password, collection, share, token_template, "share", delete_share_by_token);
+        add_share_row_node(user, password, collection, share, token_template, "share", delete_share_by_token, errorHandler);
       } else if (share["ShareType"] === "map") {
-        add_share_row_node(user, password, collection, share, map_template, "map", delete_share_by_map);
+        add_share_row_node(user, password, collection, share, map_template, "map", delete_share_by_map, errorHandler);
       }
     }
   });