Security Update for Microsoft Office 2016 (KB5002838) 32-Bit Edition Install error - 0x8007064c

Question

Saw an update for MSO 2016 available when I went to Windows Update in Settings.

Said that update failed so I retried. I almost immediately got an error message pop-up saying "Smart App Control has blocked this app mso-x-none. MSP was blocked because we can't confirm who published it and it's not an app we're familiar with". Searched the update, KB5002838 and downloaded it from the Microsoft site and tried to install it from the downloaded file and had the same issue. Why am I getting this error all of a sudden? I am still using MSO 2016 because I'm told if I want to run a later version like 2019 or 2021, I would have to uninstall it and install the new version. I do have a valid product key for a later edition of MSO, just not sure I want to go through the headache.

Answer 1

I have Microsoft Office Pro Plus 2016 which I purchased and downloaded some years ago. It has been updating since then without issues. I do not believe I have the Click-to-Run version but rather the release MSI install version. Definitely was never referred to as Microsoft 365. Can I or should I somehow turn off Smart-App Blocking to allow this to go through and then turn it back on?

Answer 2

Smart App Control is blocking the mso-x-none.msp package for the Office 2016 security update because it cannot validate the publisher for that specific installer file, so Windows is treating it as an unfamiliar or potentially unsafe app. This is why the update fails both through Windows Update and when running the downloaded .msp file directly.

For Office 2016 security updates like KB5002826/KB5002838, note the following from the documentation:

• The update package is an mso-x-none.msp file that updates core Office components such as Mso.dll, Msores.dll, and related files.
• These updates are distributed either via Microsoft Update/Windows Update or as standalone packages from the Microsoft Update Catalog.
• The standalone package applies only to MSI-based Office 2016 installations, not Click-to-Run editions such as Microsoft 365.

Given that Smart App Control is blocking the .msp installer, the supported way to receive this update is:

1. Ensure Office 2016 is the release MSI-based version (not Click-to-Run). The security update requires the release version of Office 2016 to be installed.
2. Use Microsoft Update/Windows Update with automatic updating enabled so the update is delivered and installed through the trusted Windows update channel instead of running the .msp manually.
3. If the update continues to fail with Smart App Control blocking the installer, the behavior is due to Smart App Control’s reputation-based blocking of that specific mso-x-none.msp package, not to a problem with the Office 2016 product key or version.

Remaining on Office 2016 is supported for these updates as long as the release version is installed. Installing a later perpetual version (2019/2021) would require uninstalling the existing Office 2016 first, but it is not required just to resolve this specific Smart App Control block.

---

References:

• Description of the security update for Office 2016: January 13, 2026 (KB5002826)
• March 10, 2020, update for Office 2016 (KB3213653)
• November 3, 2020, update for Office 2016 (KB4486680)
• Choose between the 64-bit or 32-bit version of Office