When switching from office 2016 to microsoft 365, it became impossible to read excel of the application created in C# normally.

是常和也 1

The specific contents of Excel reading failure are as follows.

C# program
System.Type.GetTypeFromProgID("Excel.Application")

will result in a null error.
Excel is installed, but the wrong judgment is made.

When I searched the Internet for the same content, there was the following content, but it was not resolved.

Is there any way to deal with this?

Jack J Jun 24,286 Reputation points Microsoft Vendor

2022-09-22T05:58:55.497+00:00

@是常和也 , Welcome to Microsoft Q&A, based on my test, the type is not null when I tested the code in the office 2016 or office 365. I am using the following Office 365 version. Then, what is your version of office 365?
是常和也 1 Reputation point

2022-09-23T07:18:02.163+00:00

Microsoft® Excel® for Microsoft 365 MSO (バージョン 2208 ビルド 16.0.15601.20148) 64 ビット

になります。
Jack J Jun 24,286 Reputation points Microsoft Vendor

2022-09-23T07:40:21.153+00:00

@是常和也 , thanks for the feedback, It may be related to your specific excel or computer environment. I recommend that you could give a feedback in the following forum.

https://feedbackportal.microsoft.com/feedback/forum/c23f3b77-f01b-ec11-b6e7-0022481f8472

Also, I will remove the tag dotnet-csharp because the code is no problem.

Thanks for your understanding.