Kaspersky Anti-Virus + Microsoft Windows 10 + Microsoft Office 365 Issue

Recently I had updated three of my household’s Windows 10 machines (one Surface Book 2, one custom built gaming PC, and one ASUS laptop) to the latest stable/release version of Windows (Microsoft Windows April 2018 Update). Each of machines also have a copy of Microsoft Office 365 installed, along with the latest version of Kaspersky Anti-Virus.

What I have found after the Windows 10 April 2018 Update installation; Microsoft Office 365 fails to properly recognise that I have a registered version. I can still use the products in the suite such as Word, Excel and Outlook, but am given 3 days to rectify the problem before the product runs in a limited capacity. I have the correct account logged in, the credentials are correct, and if I try to register and authenticate via the Internet option (phone option is not available) it completely fails. Googling or Binging the error code that is produced does not show any resolution or worthwhile results.

Restarting the machine, restarting any of the Microsoft Office 365 products also does not seem to resolve the problem. Initially I thought that communication to the Microsoft servers was unavailable (sometimes servers go down), but trying to use the product at any time resulted in the register/authenticate prompt to appear on all the machines. So out of sheer desperation and curiosity I thought perhaps I should disable my anti-virus because sometimes they can cause problems with certain applications. Low and behold when I booted up any of the Microsoft Office 365 products the registration/authentication prompt no longer appeared. It appeared that Kaspersky Anti-Virus was blocking or limiting my ability to properly communicate with the Microsoft servers.

Now that Microsoft Office 365 could be restarted without the register/authenticate prompt appearing I decided to re-enable my Kaspersky Anti-Virus, restart my machine and launch the Microsoft Office 365 products. Still no more register/authenticate prompts; great news. Whatever happened between the Windows 10 April 2018 Update, Kaspersky Anti-Virus and Microsoft Office 365; it seemed like it invalidated my copy of Microsoft Office 365. If you encounter the same problem after updating your Windows 10 machine then try the following steps because they worked for me:

1. Close any open Microsoft Office 365 product you have open.
2. Disable any anti-virus that you have running (if possible).
3. Open a Microsoft Office 365 product.
4. Close the Microsoft Office 365 product.
5. Turn on your anti-virus.
6. Restart your Windows 10 machine (this is optional).
7. Open a Microsoft Office 365 product (the register/authenticate pop up should no longer appear).

Hopefully the above steps helps to resolve your problem.