The solution being upgraded has a combination of .NET 4.7.2 projects (WPF) and .NET Standard 2.0 libraries where the latter refer to the Syncfusion. Xls.Net.Core Nuget package. All Syncfusion dependencies are Nuget based. The application compiled and ran successfully with V126.96.36.199 dependencies. Upgrading the projects to 188.8.131.52 Nuget dependencies succeeded and the application compiles successfully with no warnings. However at runtime the following exception is now thrown. I can produce a cut down sample application to attempt to reproduce the problem if needed. The incident has been reported without a sample project illustrating the problem in case the behaviour and reason for the issue is obvious to Syncfusion support.
Note the exception refers to 16.4200.0.42 and not 184.108.40.206 - which I found strange.
Also: There is no option to select .NET Standard or .NET Framework 4.7.* in your dropdown lists in directtrac.