Microsoft 365 and Office | Development | Other
Building custom solutions that extend, automate, and integrate Microsoft 365 apps.
VSTO-based add-in cannot load after installing the latest Windows updates
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Dan Vasilov
5
Reputation points
We are developing a VSTO-based add-in for PowerPoint. We have two sites now where the add-in no longer loads in PowerPoint. After configuring VSTO to display the error messages, PowerPoint displays the error "The common language runtime could not be loaded by file:///{path to our vsto file}|vstolocal. Contact your administrator for further assistance."
The customer has confirmed the add-in loaded fine in August. It seems the issue is caused by some of the latest Windows updates that, unfortunately, cannot be uninstalled.
What are our options? Can we obtain support from the VSTO runtime team directly? Can Microsoft temporarily unpublish the Windows updates?
Does anybody else has this issue?
Microsoft 365 and Office | Development | Other
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Romain Miroux 5 Reputation points2026-01-26T13:10:48.1166667+00:00 Hi Dan,
I understand your question was a few years ago, but I'm having the same issue and was wondering if you found the cause and solution?
Thank you!
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