diff --git a/apps/browser-extension/src/entrypoints/popup/components/Button.tsx b/apps/browser-extension/src/entrypoints/popup/components/Button.tsx
index 9f76b25d8..bdcb6bac0 100644
--- a/apps/browser-extension/src/entrypoints/popup/components/Button.tsx
+++ b/apps/browser-extension/src/entrypoints/popup/components/Button.tsx
@@ -2,6 +2,7 @@ import React from 'react';
 
 type ButtonProps = {
   onClick?: () => void;
+  id?: string;
   children: React.ReactNode;
   type?: 'button' | 'submit' | 'reset';
   variant?: 'primary' | 'secondary';
@@ -12,6 +13,7 @@ type ButtonProps = {
  */
 const Button: React.FC<ButtonProps> = ({
   onClick,
+  id,
   children,
   type = 'button',
   variant = 'primary'
@@ -26,6 +28,7 @@ const Button: React.FC<ButtonProps> = ({
       className={`${colorClasses[variant]} text-white font-medium rounded-lg px-4 py-2 text-sm w-full`}
       onClick={onClick}
       type={type}
+      id={id}
     >
       {children}
     </button>
diff --git a/apps/browser-extension/src/entrypoints/popup/pages/auth/Upgrade.tsx b/apps/browser-extension/src/entrypoints/popup/pages/auth/Upgrade.tsx
index b9ce04acd..b6d78bc19 100644
--- a/apps/browser-extension/src/entrypoints/popup/pages/auth/Upgrade.tsx
+++ b/apps/browser-extension/src/entrypoints/popup/pages/auth/Upgrade.tsx
@@ -312,6 +312,7 @@ const Upgrade: React.FC = () => {
         <div className="flex flex-col w-full space-y-2">
           <Button
             type="button"
+            id="upgrade-button"
             onClick={handleUpgrade}
           >
             {isLoading || isVaultMutationLoading ? (syncStatus || t('upgrade.upgrading')) : t('upgrade.upgrade')}
diff --git a/apps/server/Tests/AliasVault.E2ETests/Tests/Extensions/VaultOutdatedTests.cs b/apps/server/Tests/AliasVault.E2ETests/Tests/Extensions/VaultOutdatedTests.cs
deleted file mode 100644
index ed0e378a7..000000000
--- a/apps/server/Tests/AliasVault.E2ETests/Tests/Extensions/VaultOutdatedTests.cs
+++ /dev/null
@@ -1,48 +0,0 @@
-//-----------------------------------------------------------------------
-// <copyright file="VaultOutdatedTests.cs" company="aliasvault">
-// Copyright (c) aliasvault. All rights reserved.
-// Licensed under the AGPLv3 license. See LICENSE.md file in the project root for full license information.
-// </copyright>
-//-----------------------------------------------------------------------
-
-namespace AliasVault.E2ETests.Tests.Extensions;
-
-using Microsoft.EntityFrameworkCore;
-
-/// <summary>
-/// End-to-end tests for the Chrome extension involving simulating an outdated vault
-/// to check for expected error messages.
-/// </summary>
-[Parallelizable(ParallelScope.Self)]
-[Category("ExtensionTests")]
-[TestFixture]
-public class VaultOutdatedTests : BrowserExtensionPlaywrightTest
-{
-    /*/// <summary>
-    /// Tests if the extension correctly handles an outdated vault version by showing appropriate error message.
-    /// </summary>
-    /// <returns>Async task.</returns>
-    [Order(1)]
-    [Test]
-    public async Task ExtensionOutdatedVaultTest()
-    {
-        // Clear any tracked entities from previous operations.
-        ApiDbContext.ChangeTracker.Clear();
-
-        // Get the latest vault and modify its version to an outdated one.
-        var latestVault = await ApiDbContext.Vaults
-            .OrderByDescending(x => x.RevisionNumber)
-            .FirstAsync();
-
-        latestVault.Version = "1.0.0";
-        await ApiDbContext.SaveChangesAsync();
-
-        // Login to the extension.
-        var extensionPopup = await LoginToExtension(waitForLogin: false);
-
-        // Verify that the expected error message is shown.
-        await extensionPopup.WaitForSelectorAsync("text=Your vault is outdated");
-        var pageContent = await extensionPopup.TextContentAsync("body");
-        Assert.That(pageContent, Does.Contain("Your vault is outdated. Please login via the web client to update your vault."));
-    }*/
-}
diff --git a/apps/server/Tests/AliasVault.E2ETests/Tests/Extensions/VaultUpgradeTests.cs b/apps/server/Tests/AliasVault.E2ETests/Tests/Extensions/VaultUpgradeTests.cs
new file mode 100644
index 000000000..8491885ed
--- /dev/null
+++ b/apps/server/Tests/AliasVault.E2ETests/Tests/Extensions/VaultUpgradeTests.cs
@@ -0,0 +1,121 @@
+//-----------------------------------------------------------------------
+// <copyright file="VaultUpgradeTests.cs" company="aliasvault">
+// Copyright (c) aliasvault. All rights reserved.
+// Licensed under the AGPLv3 license. See LICENSE.md file in the project root for full license information.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace AliasVault.E2ETests.Tests.Extensions;
+
+using AliasServerDb;
+
+/// <summary>
+/// End-to-end tests for upgrading vaults in the browser extension.
+/// </summary>
+[Parallelizable(ParallelScope.Self)]
+[Category("ExtensionTests")]
+[TestFixture]
+public class VaultUpgradeTests : BrowserExtensionPlaywrightTest
+{
+    /// <summary>
+    /// Gets or sets user email (override).
+    /// </summary>
+    protected override string TestUserUsername { get; set; } = "testdbupgrade@example.com";
+
+    /// <summary>
+    /// Gets or sets user password (override).
+    /// </summary>
+    protected override string TestUserPassword { get; set; } = "password";
+
+    /// <summary>
+    /// Test if a version 1.0.0 vault can be unlocked and upgraded in the browser extension.
+    /// </summary>
+    /// <returns>Async task.</returns>
+    [Test]
+    public async Task ExtensionVaultUpgrade100Test()
+    {
+        // Define service names that are stored in the vault and expected to be shown after upgrade.
+        List<string> expectedServiceNamesInVault =
+        [
+            "Test credential 1",
+            "Test credential 2",
+        ];
+
+        // Clear any tracked entities from previous operations.
+        ApiDbContext.ChangeTracker.Clear();
+
+        // Insert static 1.0.0 vault into the database for the current user.
+        ApiDbContext.Vaults.Add(
+            new Vault
+            {
+                Id = Guid.NewGuid(),
+                UserId = ApiDbContext.AliasVaultUsers.First().Id,
+                Version = "1.0.0",
+                RevisionNumber = 2,
+                CreatedAt = DateTime.UtcNow,
+                UpdatedAt = DateTime.UtcNow,
+                EncryptionType = "Argon2Id",
+                EncryptionSettings = "{\"DegreeOfParallelism\":4,\"MemorySize\":8192,\"Iterations\":1}",
+                VaultBlob = await ResourceReaderUtility.ReadEmbeddedResourceStringAsync("AliasVault.E2ETests.TestData.AliasClientDb_encrypted_base64_1.0.0.txt"),
+                Salt = "1a73a8ef3a1c6dd891674c415962d87246450f8ca5004ecca24be770a4d7b1f7",
+                Verifier = "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",
+            });
+        await ApiDbContext.SaveChangesAsync();
+
+        // Login to the extension.
+        var extensionPopup = await LoginToExtension(waitForLogin: false);
+
+        // Wait for vault upgrade UI to appear.
+        await extensionPopup.WaitForSelectorAsync("text=vault needs to be upgraded", new() { Timeout = 10000 });
+
+        // Verify the upgrade message is shown.
+        var pageContent = await extensionPopup.TextContentAsync("body");
+        Assert.That(pageContent, Does.Contain("vault needs to be upgraded"), "Expected vault upgrade message not found");
+
+        // Click the upgrade button.
+        var upgradeButton = extensionPopup.Locator("button[id='upgrade-button']").First;
+        await upgradeButton.ClickAsync();
+
+        // Wait for confirm button
+        await extensionPopup.WaitForSelectorAsync("text=Continue Upgrade", new() { Timeout = 15000 });
+
+        // Click the upgrade button.
+        var upgradeConfirmButton = extensionPopup.Locator("text=Continue Upgrade").First;
+        await upgradeConfirmButton.ClickAsync();
+
+        // Wait for upgrade to complete and credentials to show.
+        await extensionPopup.WaitForSelectorAsync("text=Test credential 1", new() { Timeout = 15000 });
+
+        // Wait for all credential cards to fully render.
+        await Task.Delay(150);
+
+        // Check if the expected service names still appear after upgrade.
+        var upgradePageContent = await extensionPopup.TextContentAsync("body");
+        foreach (var serviceName in expectedServiceNamesInVault)
+        {
+            Assert.That(upgradePageContent, Does.Contain(serviceName), $"Credential name '{serviceName}' which existed in 1.0.0 encrypted vault does not appear in extension after database upgrade. Check extension DB migration logic for potential data loss.");
+
+            // Find and click on the credential to verify it's accessible.
+            var credentialElement = await extensionPopup.WaitForSelectorAsync($"text={serviceName}");
+            Assert.That(credentialElement, Is.Not.Null, $"Could not find credential element for service '{serviceName}'");
+
+            // Click on the credential to open details.
+            await credentialElement.ClickAsync();
+
+            // Wait for the credential details to load.
+            await Task.Delay(150);
+
+            // Check if the service name appears in the details view.
+            var detailsContent = await extensionPopup.TextContentAsync("body");
+            Assert.That(detailsContent, Does.Contain(serviceName), $"Service name '{serviceName}' not found on the credential details view");
+
+            // Navigate back to the list.
+            var backButton = await extensionPopup.QuerySelectorAsync("button[id='back']");
+            if (backButton != null)
+            {
+                await backButton.ClickAsync();
+                await Task.Delay(150);
+            }
+        }
+    }
+}