Outlook 2016: Calendar access blocked after April 2025 update KB5002700

[German]On April 8, 2025, Microsoft released the Office update KB5002700 to close a number of vulnerabilities in Microsoft Office 2016. After installing this update, access to the calendar is no longer possible. However, there is a quick workaround.

Office 2016 Update KB5002700

Update KB5002700 for Microsoft Office 2016 was released on April 8, 2025. It closes a remote code vulnerability. a privilege elevation vulnerability in Microsoft Office, a security feature bypass vulnerability in Microsoft Word, and a remote code execution vulnerability in Microsoft Excel. Here is the list of vulnerabilities that are addressed:

The installation of the security update should actually be necessary.

Crashes with Outlook calendar

I got several reports from German users, mention issues with this update. German blog reader Jörg contacted me on April 9, 2025 and wrote that since the patchday [April 8, 2025] it is no longer possible to access the Outlook calendar. He tested it with Outlook 2016 (16.0.5483.1000 / 32Bit) from Office 2016 (volume license / MSI installation) in combination with Exchange On-Premises.

Jörg writes that the problem occurs with several customers. As soon as you click on the calendar in Outlook, the calendar appears very briefly – then Outlook crashes completely. It does not seem to be due to the Windows version – both Outlook under Windows 11 24H2 and e.g. Windows 10 22H2 are affected according to Jörg (thanks for the information). Further users have responded to the blog post, confirming the behavior. Another user has commented that this problem is related to the security update.

Workaround: Disable weather integration

In the comments to my German edition of this blog post, Norman and Björn, for example, point out that the problem is due to the weather integration in the calendar (thanks for pointing this out). The workaround is quite simple: Open Microsoft Outlook, then select File-> Options-> Calendar, scroll to the bottom and uncheck the Show weather option.

Addendum: The issues has been fixed with another update, see Office 2016 update KB5002623 fixes crashes in Excel, Outlook, Word (April 10, 2025).

Similar articles:
Microsoft Security Update Summary (April 8, 2025)
Patchday: Windows 10/11 Updates (April 8, 2025)
Patchday: Windows Server-Updates (April 8, 2025)
Patchday: Microsoft Office Updates (April 8, 2025)

Word/Excel 2016 crashing after April 2025 update KB5002700
Outlook 2016: Calendar access blocked after April 2025 update KB5002700

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17 Responses to Outlook 2016: Calendar access blocked after April 2025 update KB5002700

  1. fd says:

    Not only … with this KB we have 100% crash on "new mail".

  2. Mehr says:

    We got word that crash at as soon as it opens. Any workarounds for that?

    The outlook calender fix, disabling weather integration, helped for outlook. But i cant find a solution for word…

  3. bruce says:

    winword.exe /safe and uncheck adobe pdf maker fixes it. this seems to affect only adobe acrobat pro version people who have it installed

  4. Francis Soen says:

    Worked for me. Thanks. Also ran into issue with Word where it closes as soon as it opens. Issue for us was Acrobat 2017 Add-in. Disabled that add-in while running word in safe mode and that fixed the issue.

  5. Kirk says:

    Works for me too. Outlook 2016 on window 10 with hybrid Exchange. Disabled the weather in outlook calendar through gpo, problem solved. Thanks

  6. Craig Musgrove says:

    Disable weather integration!! Fixed!!
    Wow.. amazing MS says see you next week on this while us guys in the trenches have to figure it out!!
    Tip of the hat to the guy who found this fix!! I would love to know how he discovered it!

  7. I. says:

    After the fix I was unable open connected Calendars, so I did restart Outlook and error is back.

  8. Paul Smith says:

    Thank you, you're a saviour!

  9. Maciej says:

    Works for me too. Thanks.

  10. ID says:

    I have found it is not problem of KB5002700, which can be solved as mentioned, but problem of KB5055661.
    When You disable calendar, You must have KB5002700, if You have KB5055661 only, it does not help

  11. Brandon says:

    Since the 4/8/25 reported KB5002700 issue at my company this has caused the previous 3/11 KB5002662 to break, possibly from the antivirus vendor we go through. We were fine on the 3/11 update up until KB5002700 was released. Users are getting a BSOD when trying to save an Excel or Word file on a network drive. Locally it works fine.

  12. raimundo Salas says:

    Update for Microsoft Office 2016 (KB5002623) this will fix the problem

  13. default user says:

    Thanks, the workaround works for us as well!

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