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unable to open .msix file that I have been able to open before

Byrd Nicholson 0 Reputation points
2026-05-19T16:17:16.7933333+00:00

I have an account with Fidelity Investments and have used Active Trader Pro+. Now I am unable to access Active Trade Pro + because it doesn't know have an application to open the .msix file.

Windows for home | Windows 10 | Settings
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  1. Lychee-Ng 20,950 Reputation points Microsoft External Staff Moderator
    2026-05-20T10:45:37.9333333+00:00

    Hi Byrd Nicholson,

    I understand how confusing it can be when an app that worked fine before now doesn't. The AI answer has given some basic troubleshooting, so besides those, here are a few steps you can try:

    1 - Reinstall or update App Installer

    • Make sure you are on a recent Windows 10 version
    • Open Microsoft Store > Library > Get updates
    • Search for App Installer > If you see it, click Update
    • If you don’t, install directly: App Installer - Microsoft Apps
    • Restart your PC after installing > try opening the .msix file again.

    2 - Try installing via PowerShell

    • Press Win + X > open Windows PowerShell / Terminal (Admin)
    • Run Add-AppxPackage -Path "C:\<path to the file.msix>"
    • Replace the path with the location of your file.

    3 - Re-download the installer

    • The file may be outdated or corrupted.
    • Download the latest installer again from Fidelity.

    .msix files are normally handled by the built‑in App Installer, so if Windows says it doesn’t know how to open the file, that component may be corrupted. If you can, let me know the exact error message you see when opening the file.

    If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

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  2. AI answer

    2026-05-19T16:17:34.0633333+00:00

    On Windows 10, .msix files are modern app packages that are installed by the OS. If a .msix file that used to install or open now fails with “no application to open this file,” treat it as an MSIX installation issue.

    Follow these steps:

    1. Run the installer as Administrator
      • Right‑click the .msix file and select Run as administrator.
      • If the package requires a per‑machine install and it’s run as a standard user, installation can fail with access issues. Running elevated ensures Windows can register the package correctly.
    2. Check for access/permission issues (error 0x80070005) If an error like 0x80070005 – Access denied appears when installing:
      • Make sure the account is an administrator.
      • Temporarily disable real‑time scanning in any antivirus/security software or add an exclusion for the .msix file, then try again.
      • Ensure the .msix file is stored in a location where the account has read access (for example, move it to a local folder like C:\Users\<user>\Downloads).
    3. Re‑download the installer
      • The .msix file may be corrupted or outdated. Download the latest Active Trader Pro+ installer from Fidelity again and retry the install.
    4. If the app was previously installed but now won’t start
      • After a system change (for example, System Restore), MSIX apps can show errors like “This app can’t open,” appear multiple times in Start, or fail to respond.
      • Workarounds:
        • Try starting the app again from Start > All apps > Active Trader Pro+.
        • If it still fails, uninstall the app (Settings > Apps > Installed apps), then reinstall it using the .msix installer.
        • Run Windows Update to ensure the system has the latest servicing updates, then reinstall and try again.

    If none of these steps work, contact Fidelity support and provide details of any error codes shown when running the .msix file so they can confirm compatibility and provide an updated installer if needed.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

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