Resolve errors and warnings for new expressions and object creation

This article covers the following compiler errors and warnings:

• CS0144: Cannot create an instance of the abstract type or interface 'type'
• CS0712: Cannot create an instance of the static class 'type'
• CS1526: A new expression requires an argument list or (), [], or {} after type
• CS8181: 'new' cannot be used with tuple type. Use a tuple literal expression instead.
• CS8386: Invalid object creation
• CS8752: The type 'type' may not be used as the target type of new()
• CS8753: Use of new() is not valid in this context
• CS8754: There is no target type for 'expression'

Types that can't be instantiated

• CS0144: Cannot create an instance of the abstract type or interface 'type'
• CS0712: Cannot create an instance of the static class 'type'

The new operator can only create instances of concrete, non-static types. The language prohibits instantiating abstract classes, interfaces, and static classes because these types are incomplete or aren't designed to have instances.

• Create a concrete class that derives from the abstract class, or create a class that implements the interface, then instantiate that concrete type (CS0144). You can't use new directly on an abstract class or an interface because they don't provide complete implementations. If you own the type, you can also remove the abstract modifier to make the class directly instantiable.
• Remove the new expression and access the static class members directly through the class name (CS0712). Static classes exist solely to group static members and can't be instantiated. If you need an instance, remove the static modifier from the class declaration.

For more information, see abstract, interface, and Static Classes and Static Class Members.

new expression syntax errors

• CS1526: A new expression requires an argument list or (), [], or {} after type
• CS8181: 'new' cannot be used with tuple type. Use a tuple literal expression instead.
• CS8386: Invalid object creation

These errors occur when the syntax of a new expression is malformed or when you use new with a type that requires a different creation syntax.

• Add an argument list (), array dimensions [], or an initializer {} after the type name in a new expression (CS1526). The new operator requires one of these to indicate how the object is constructed. For example, write new MyClass() instead of new MyClass.
• Replace new (int, string)(...) with a tuple literal expression like (1, "hello") (CS8181). Tuple types use a dedicated literal syntax rather than the new operator. To create a tuple, use parenthesized values directly: (int X, string Y) point = (1, "hello");.
• Ensure the new expression targets a valid constructible type (CS8386). This error occurs when the compiler can't determine a valid object creation from the syntax. Verify you're using a type name that supports construction, and that the expression is syntactically complete.

For more information, see new operator and Tuple types.

Target-typed new expressions

• CS8752: The type 'type' may not be used as the target type of new()
• CS8753: Use of new() is not valid in this context
• CS8754: There is no target type for 'expression'

Target-typed new expressions (introduced in C# 9) let you omit the type name when the compiler can infer it from context, as in MyClass x = new();. These errors occur when the compiler can't determine a valid target type or when the inferred type isn't constructible.

• Use an explicit type name instead of target-typed new() when the target type is an interface, abstract class, static class, or other non-constructible type (CS8752). Target-typed new() infers the type from the left-hand side, but the inferred type must be a concrete, instantiable type. Write the full new ConcreteType() instead.
• Move the new() expression to a context where a target type is available (CS8753). Target-typed new is valid only in contexts where the compiler can determine a type, such as variable declarations with an explicit type, assignment expressions, return statements with a known return type, or argument positions with a known parameter type. You can't use new() in contexts like var x = new(); where no target type exists.
• Provide an explicit type for the new expression when no target type can be inferred (CS8754). This error occurs when you use new() in a position where the compiler has no way to determine what type to construct. Replace new() with new ExplicitType(), or declare the variable with an explicit type rather than var.

For more information, see Target-typed new expressions.