Hello.

It still puzzles why the license change should have effect. But anyway, if they have not changed the version of the software, why were they swapping in a new license? And if this is really somehow related to the license (I do not believe it), why don't they swap in the old one back, at least to test it out?

Since it is a Windows Service, I can hypothesize that the issue can be related to permissions to the certificate stores (or their contents).

I assume they do not change the store locations from the code and they stay with the defaults? - please confirm.

Can they, just for test, switch the account under which the service running, to a normal user account?

And, before doing that, can they provide a directory of files and folders under "C:\ProgramData\OPC Foundation" - if that exists at all?

Best regards

Hello,
yes, please find out whether the customer is using .NET Framework or .NET Core.

I understand that the problem appeared after "applying" a new license, but I do not see how the license could affect the problem. Wasn't is rather an upgrade of the software version itself that has triggered it?

Unfortunately, Microsoft message texts from the cryptography part often do not reflect the true cause of the problem. I suspect that "The requested key container was not found." also does not really mean what it says. And yes, it is most likely a problem different from the link you have also found.

I do not know the cause but we will try to narrow it down. Some additional questions:

1. What kind of application is the user project? (such as Windows Forms app, Console app, Windows service, Web app, Web service etc.).
2. Does it run under the normal user account (the interactive user), or under some other account?

Regards