I have updated some legacy VB/ASP.NET code and changed the references of InterSystems.Data.CacheClient to InterSystems.Data.IRISClient. I am struggling with the code as I am not a .NET expert and there is little or no documentation.
I have published the code on several test IIS sites and on some the code works fine but on others I get the below error. The error doesn't appear to be O/S specific as I have it working on some Windows 2016 servers and not working on other Windows 2016 servers.

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