Class '<classname>' must declare a 'Sub New' because the '<constructorname>' in its base class '<baseclassname>' is marked obsolete
A class declaration does not include a constructor, and the base class constructor is marked with the ObsoleteAttribute attribute and the directive to treat it as an error.
When a derived class does not declare a constructor, Visual Basic attempts to generate an implicit parameterless constructor that calls MyBase.New(). If there is no accessible constructor in the base class that can be called without arguments, Visual Basic cannot generate an implicit constructor. In this case, the required constructor is marked with the ObsoleteAttribute attribute, so Visual Basic cannot call it.
You can mark any programming element as being no longer in use by applying ObsoleteAttribute to it. If you do this, you can set the attribute's IsError property to either True or False. If you set it to True, the compiler treats an attempt to use the element as an error. If you set it to False, or let it default to False, the compiler issues a warning if there is an attempt to use the element.
Error ID: BC30917
To correct this error
Use Sub New to declare a constructor in the derived class.