Excel based application doesn't work after Office 365 auto updates are pushed

Question

Hi,

We have a .NET application which embeds Excel inside of it. Generally, our application is installed in PCs running in plants and they are in isolated network. So our application needs only desktop version of Excel. Some of our application engineers use corporate laptops to configure our application and then load the projects on to the plant systems. These laptops run Office 365 as mandated by our organization. Because of frequent automatic updates pushed by Office 365, our application is failing to start with the error below. On debugging I found that the registration of few .XLL modules using Microsoft.Office.Interop.Excel.Application.RegisterXLL is failing. We are not sure what is the root cause of this issue and how it is related to Office 365 but issue popped up only after Office 365 updates. Please help us overcome this error.

Answer 1

@Rajaiah

Since your issue may be related to the third-party software, which means we do not have the same test environment.

From the perspective of Office, you could try to roll back office to the previous version.
Press Windows + R in the search bar, type the following command, click ‘OK’.
"C:\Program Files\Common Files\microsoft shared\ClickToRun\OfficeC2RClient.exe" /update user updatetoversion=#########
(######### is the previous Office version number like 16.0.12430.20264)

I would recommend you to post your issue on the Excel for developers forum and Office for developers forum.
Maybe some experienced people will communicate with you there.

If you have any updates, you could also share the solution on this thread.

Thanks for your understanding.

Regards,
Erin

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