'variable' is of type 'type'. A const field of a reference type other than string can only be initialized with null.
A constant-expression is an expression that can be fully evaluated at compile-time. Because the only way to create a non-null value of a reference-type is to apply the new operator, and because the new operator is not permitted in a constant-expression, the only possible value for constants of reference-types other than string is null.
If you encounter this error by trying to create a const string array, the solution is to make the array readonly, and initialize it in the constructor.