diff --git a/src/Umbraco.Core/Models/ContentEditing/PropertyTypeBasic.cs b/src/Umbraco.Core/Models/ContentEditing/PropertyTypeBasic.cs
index 4574e62cde4a..a09cb0a300c0 100644
--- a/src/Umbraco.Core/Models/ContentEditing/PropertyTypeBasic.cs
+++ b/src/Umbraco.Core/Models/ContentEditing/PropertyTypeBasic.cs
@@ -25,6 +25,7 @@ public class PropertyTypeBasic
 
     [Required]
     [RegularExpression(@"^([a-zA-Z]\w.*)$", ErrorMessage = "Invalid alias")]
+    [MaxLength(255, ErrorMessage = "Alias is too long")]
     [DataMember(Name = "alias")]
     public string Alias { get; set; } = null!;
 
diff --git a/src/Umbraco.Web.UI.Client/src/views/components/umb-locked-field.html b/src/Umbraco.Web.UI.Client/src/views/components/umb-locked-field.html
index 9c4e694335af..b60bc0c13c5c 100644
--- a/src/Umbraco.Web.UI.Client/src/views/components/umb-locked-field.html
+++ b/src/Umbraco.Web.UI.Client/src/views/components/umb-locked-field.html
@@ -25,7 +25,8 @@
                title="{{ngModel}}"
                focus-when="{{!locked}}"
                umb-select-when="{{!locked}}"
-               ng-blur="lock()" />
+               ng-blur="lock()"
+               ng-maxlength="255" />
 
     </div>
 
@@ -46,6 +47,11 @@
              ng-if="serverValidationField.length > 0"
              ng-message="valServerField">{{lockedFieldForm.lockedField.errorMsg}}
         </div>
+        <div class="umb-validation-label"
+             ng-class="{ '-left': validationPosition === 'left', '-right': validationPosition === 'right' }"
+             ng-if="ngModel.length > 255">
+            <localize key="general_invalid">Invalid</localize> <localize key="content_alias">alias</localize>
+        </div>
     </div>
 
 </ng-form>