Not loaded. A runtime error occurred during the loading of the COM add-in.

[BluePointLilac]

Same problem as in the link.

The same plug-in DLL, written in C# .NET, may load successfully in Word, Excel, and PowerPoint but fail to load in Outlook. It may also be the opposite, or it may not load successfully at all.
A complete reinstall of Office may solve the problem, but it is not guaranteed.
Is there a more detailed error report, how to locate the cause of this problem, and how to solve the problem of plug-in failure to load.

[Rick-Kirkham]

Phoebe, can you please see if you can find some help for this COM add-in developer?

@BluePointLilac We use the issues in the repo to track problems with the documentation for Office web add-ins, not problems with COM add-ins. But I will leave it open for now, so @grangeryy can communicate with you.

[grangeryy]

Also adding @qinliuMSFT