diff --git a/src/OutlookAddin.UI/ViewModels/SettingsViewModel.cs b/src/OutlookAddin.UI/ViewModels/SettingsViewModel.cs
index 7ac8530..504b5b4 100644
--- a/src/OutlookAddin.UI/ViewModels/SettingsViewModel.cs
+++ b/src/OutlookAddin.UI/ViewModels/SettingsViewModel.cs
@@ -216,22 +216,39 @@ namespace MarcusLaw.OutlookAddin.UI.ViewModels
 
                 // VSTO add-ins cannot be updated programmatically from inside
                 // a running Outlook — ApplicationDeployment.Update() throws.
-                // Open the .vsto URL via the shell; Windows hands it to
-                // VSTOInstaller.exe which installs the update correctly.
-                try
+                // Don't shell-launch the .vsto URL either: Chrome / Edge will
+                // download it to disk, and the resulting file has a different
+                // security zone than the deployment manifest, which fails with
+                // InvalidDeploymentException ("no matching security zones").
+                // Call VSTOInstaller.exe directly so the URL is processed in
+                // the Internet zone, matching the manifest.
+                var installerPath = FindVstoInstaller();
+                if (installerPath != null)
                 {
-                    System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo(manifestUri.ToString())
+                    try
                     {
-                        UseShellExecute = true
-                    });
-                    UpdateStatusBrush = SuccessBrush;
-                    UpdateStatus = $"זמינה גרסה {availableVersion} — אשר את ההתקנה בחלון שנפתח, ואז סגור ופתח את Outlook.";
+                        System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo(
+                            installerPath, "/I \"" + manifestUri + "\"")
+                        {
+                            UseShellExecute = false
+                        });
+                        UpdateStatusBrush = SuccessBrush;
+                        UpdateStatus = $"זמינה גרסה {availableVersion} — אשר את ההתקנה בחלון שנפתח, ואז סגור ופתח את Outlook.";
+                    }
+                    catch (Exception launchEx)
+                    {
+                        _logger.Warning(launchEx, "CheckForUpdate: VSTOInstaller launch failed");
+                        UpdateStatusBrush = ErrorBrush;
+                        UpdateStatus = $"זמינה גרסה {availableVersion} — סגור ופתח את Outlook כדי להתקין אוטומטית.";
+                    }
                 }
-                catch (Exception launchEx)
+                else
                 {
-                    _logger.Warning(launchEx, "CheckForUpdate: shell launch of installer URL failed");
-                    UpdateStatusBrush = ErrorBrush;
-                    UpdateStatus = $"זמינה גרסה {availableVersion} אבל לא הצלחנו לפתוח את חלון ההתקנה. גש ידנית ל-{manifestUri}";
+                    // VSTOInstaller not at the canonical path — VSTO runtime
+                    // still picks up new manifests on Outlook startup, so
+                    // ask the user to restart instead of attempting a hack.
+                    UpdateStatusBrush = SuccessBrush;
+                    UpdateStatus = $"זמינה גרסה {availableVersion} — סגור ופתח את Outlook כדי להתקין אוטומטית.";
                 }
                 return;
             }
@@ -286,6 +303,50 @@ namespace MarcusLaw.OutlookAddin.UI.ViewModels
             }
         }
 
+        /// <summary>
+        /// Locates VSTOInstaller.exe on the machine. The path is stable
+        /// for VSTO 4.0 (Office 2010+) — falls back to a registry lookup
+        /// if the default install location was customised.
+        /// </summary>
+        private static string? FindVstoInstaller()
+        {
+            string[] candidates =
+            {
+                @"C:\Program Files (x86)\Common Files\Microsoft Shared\VSTO\10.0\VSTOInstaller.exe",
+                @"C:\Program Files\Common Files\Microsoft Shared\VSTO\10.0\VSTOInstaller.exe"
+            };
+            foreach (var p in candidates)
+            {
+                if (System.IO.File.Exists(p)) return p;
+            }
+
+            // Registry fallback: HKCR\VstoFile\shell\Open\command stores
+            // the verb VSTOInstaller registers for the .vsto extension.
+            try
+            {
+                using (var key = Microsoft.Win32.Registry.ClassesRoot.OpenSubKey(@"VstoFile\shell\Open\command"))
+                {
+                    var cmd = key?.GetValue(null) as string;
+                    if (!string.IsNullOrEmpty(cmd))
+                    {
+                        // Value looks like: "C:\...\VSTOInstaller.exe" "%1"
+                        var firstQuote = cmd!.IndexOf('"');
+                        if (firstQuote == 0)
+                        {
+                            var endQuote = cmd.IndexOf('"', 1);
+                            if (endQuote > 1)
+                            {
+                                var exe = cmd.Substring(1, endQuote - 1);
+                                if (System.IO.File.Exists(exe)) return exe;
+                            }
+                        }
+                    }
+                }
+            }
+            catch { /* registry access denied or schema differs — fall through */ }
+            return null;
+        }
+
         private bool CanCheckForUpdate() => !IsCheckingForUpdate;
 
         partial void OnIsCheckingForUpdateChanged(bool value)
diff --git a/src/OutlookAddin/OutlookAddin.csproj b/src/OutlookAddin/OutlookAddin.csproj
index a2d8e1d..2273dcf 100644
--- a/src/OutlookAddin/OutlookAddin.csproj
+++ b/src/OutlookAddin/OutlookAddin.csproj
@@ -36,7 +36,7 @@
     <PublishUrl>C:\Users\Chaim\source\repos\OutlookAddin\Publish\</PublishUrl>
     <InstallUrl>https://gitea.dev.marcus-law.co.il/espocrm-extensions/OutlookAddin/raw/branch/main/Publish/</InstallUrl>
     <TargetCulture>en</TargetCulture>
-    <ApplicationVersion>1.2.4.0</ApplicationVersion>
+    <ApplicationVersion>1.2.5.0</ApplicationVersion>
     <AutoIncrementApplicationRevision>false</AutoIncrementApplicationRevision>
     <UpdateEnabled>true</UpdateEnabled>
     <UpdateInterval>7</UpdateInterval>
diff --git a/src/OutlookAddin/Properties/AssemblyInfo.cs b/src/OutlookAddin/Properties/AssemblyInfo.cs
index ab2636a..d3f7075 100644
--- a/src/OutlookAddin/Properties/AssemblyInfo.cs
+++ b/src/OutlookAddin/Properties/AssemblyInfo.cs
@@ -33,6 +33,6 @@ using System.Security;
 // You can specify all the values or you can default the Build and Revision Numbers 
 // by using the '*' as shown below:
 // [assembly: AssemblyVersion("1.0.*")]
-[assembly: AssemblyVersion("1.2.4.0")]
-[assembly: AssemblyFileVersion("1.2.4.0")]
+[assembly: AssemblyVersion("1.2.5.0")]
+[assembly: AssemblyFileVersion("1.2.5.0")]