Excel: Automation add-ins are not loading after the April 2021 security update
Summary
Microsoft lists a known issue in which Automation add-ins for Excel do not load after the April 2021 security update is installed. Microsoft marks the issue with the status Workaround. The excerpt available does not describe the workaround steps.
Symptoms
Automation add-ins for Excel are not loaded after the April 2021 security update is installed.
Affected
- Excel (Microsoft 365 Apps) with the April 2021 security update installed
- Exact versions and builds: not stated in the available source excerpt
Workaround
Microsoft documents a workaround. The steps are not included in the available excerpt, so please refer to the Microsoft article.
Fix
No fix is stated in the available source excerpt.
Recommendation
Check whether business-critical Automation add-ins are in use. Open the Microsoft article, review the documented workaround and test it on a pilot device before rolling it out.
Sources
- Microsoft 365 Apps: bekannte Probleme Excel Vendor · support.microsoft.com
Compiled from the sources listed and translated with AI (Claude); status and dates come from the vendor. The vendor’s statements are authoritative. Updated 1 Nov 2026, 18:21.
Where the information comes from
We continuously read the vendors’ official sources, community reports and trade media and summarise them in our own words, with a link to the source:
- Microsoft: Windows release health (Windows 10/11, Server 2016 to 2025), Windows message center, known issues of Microsoft 365 Apps (Outlook, Excel, Word, PowerPoint), Edge, Intune, Autopilot, Windows 365 and Entra Connect, Microsoft KB articles with timelines, Exchange and Windows IT Pro blogs, optionally Microsoft 365 service health and message center
- other vendors: Veeam KB, Citrix (known issues), Ubuntu and Debian (regressions), Broadcom (VMware), Fortinet, Cisco, Mozilla, Let’s Encrypt
- community (title, short excerpt and link only, without the names of the authors): Microsoft Q&A, Microsoft Tech Community (discussions), Veeam R&D Forums, Eleven Forum
- targeted web research with AI (Claude), e.g. on the updates of the month – this also finds discussions on Reddit and in forums; such entries are labelled as community reports until the vendor confirms them
- early warning from trade media (title and link only): Born’s Tech and Windows World, BleepingComputer, AskWoody, Windows Latest, Windows Central, gHacks, The Windows Club, Deskmodder, Dr. Windows, WindowsArea, Frankys Web, heise online
Summary and translation with AI (Claude by Anthropic) – without any data of visitors.
Affected? We can help.
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