EF Net Core does not support nvarchar

I got this problem earlier today and i could swore it only happens for .net core 2.0. The message looks something like this :-

Data type 'nvarchar' is not supported in this form" after scaffolding from database 

After my model is binded or built, it throws this exception. I change

///

  entity.Property(e => e.Comments)
                .HasColumnName("Comments")
                .HasColumnType("nvarchar"); // No size specifier 

to

  entity.Property(e => e.Comments)
                .HasColumnName("Comments")
                .HasColumnType("nvarchar(4000)"); // <- add="" span="" this="">

And it was working. Do not think this affect a single table, it affects ALL table. So please find and replace all.

Not really sure what is the work about. Maybe i should try it on .net core 2.1.1 etc.

Hope this helps.