19H1 Build 18358- Application Guard Extension for Firefox and Chrome

Windows 10 Insider 19H1 Build 18358 comes with new game fixes and a new extension for browsers such as- Mozilla Firefox and Google Chrome. Microsoft has developed “Application Guard Extension” as a part of Windows Defender. Insiders who have opted for fast rings can run this app after installing 19H1 Build 18358 on their System.

The company has also made some improvements which we will see later on this article along with some known issues. So, let’s explore this Windows 10 Insider Build 18358 (1903) in detail-

19H1 Build 18358

What’s new in 19H1 Build 18358

Microsoft has extended its container technology for users to apply on their top browsers like Firefox and Chrome. This will help them by providing a comprehensive solution to several phishing and malware attacks that often occur while browsing through net. This new Windows Defender- Application Guard extension will soon appear in the Add-on section of Web browser.

How this will work

If you use this extension on your Web-surfing platforms, they will redirect any untrusted navigation to Application Guard for moderation. This add-on relies on an in-built program which bridges the communication between Browser and Application Guard Settings.

Let’s say you navigate through a website then this extension will check its URL with the norms laid out by different Enterprise Administrators. If it finds some issue, it will redirect the webpage to Microsoft Session (isolated with the current session). Here, in this isolated session, users can freely browse to whatsoever they want to without disturbing the existing ecosystem of Windows.

The vice-versa is also applicable with its upcoming dynamic switching capability. It simply implies that whenever you go for a trusted website in Microsoft edge, this will take you back to your default browser.

Application Guard Extension

Enterprise Administrator may follow these steps to configure this extension under manage mode-

  1. It should meet the minimum requirements.
  2. Windows Defender Application Guard must be Turned On.
  3. To ensure a list of trusted websites, define the Network Isolation Settings.
  4. Install the new Windows Defender app from Microsoft Store.
  5. Install the extension as per your convenient browsers like- Firefox and Chrome.
  6. Reboot your devices.

Intuitive user experience

The user interface of this extension is really smooth and intriguing. The best thing about this extension is that it lets users know what exactly is this exist for and what will be its principle operands. Only untrusted navigation will be moved to an isolated session and here are some tips for users-

19H1 Build 18358

  1. Users will see the Application guard extension landing page once they have added this extension on their browsers-Firefox or Chrome.
  2. If there occurs any configuration trouble, users will get proper instructions to resolve such errors.
  3. They can initiate this extension even before typing a URL/ clicking on a link by simple activating the extension icon available at browser’s menu bar.

Where to get Windows Defender App Guard

Microsoft is already rolling out this extension starting from today. In case, you haven’t received the same, wait for a few more days. This will be available only for Windows 10 Pro and Enterprise users.

General changes, improvements, and fixes for PC

For Game Lovers

  1. They have fixed an issue which causes trouble while smooth streaming or quality recording of games.
  2. If you have not played State of Decay game, you have the opportunity to download the same for free. The Company has added a few more slots for new users. You can read these instructions to understand the basics of game-play.
  3. They added a new version of this game for Insiders and they are going to update this on its upcoming releases. You can navigate to Store –> Downloads and Updates to have this game.

Some other fixes- 19H1 Build 18358

  • Microsoft fixed the Alt+Tab hotkey which helps us to migrate from one tab to another.
  • They have fixed an issue where some files of Recycle Bin are kept under windows.old folder after an update.
  • They also solved the issue which results in GSOD bug check with KERNEL_SECURITY_VIOLATION.
  • The Company rectified the rolling back update error stuck at 18% or 25%.

Known issues

  1. There is still GSOD error while launching games with anti-cheat programs.
  2. Creative X-Fi sound and Realtek SD cards are yet not working properly on this 19H1 Build 18358.
  3. Users should continue using Hyper-V as an alternate solution for VMware to install or update Windows 10 recent builds on their PC.
  4. From 19H1 Build 18356 onwards, users won’t get updates for Microsoft Store automatically. However, they can update the same manually. Navigate to the path-
Three dot icon (...) --> Downloads and Updates --> Get Updates

In this way, you can update your Store app on the System.

Known issues for Developers

This section remains the same. In case, you revert back to slow ring after installing any recent Build from the Fast ring, optional content may not function. This occurs because they are not approved for specific rings, hence, you won’t be able to add, install or enable optional content.


Finally, a good and nice feature, Windows Defender-Application Guard Extension comes with Windows 10 Insider 19H1 Build 18358. Go give this a try and submit your feedback to Microsoft. You can comment here as well if you don’t understand a part of this article.