The annotation for nullable reference types should only be used in code within a '#nullable' annotations context.

The annotation for nullable reference types should only be used in code within a '#nullable' annotations context.

The annotation for nullable reference types should only be used in code within a '#nullable' annotations context.

'Exception.Exception(SerializationInfo, StreamingContext)' is obsolete: 'This API supports obsolete formatter-based serialization. It should not be called or extended by application code.' (https://aka.ms/dotnet-warnings/SYSLIB0051)