FTPError: 550 There is not enough space on the disk.

The type 'ChessTourManager.DataAccess.Entities.Tournament?' cannot be used as type parameter 'TEntity' in the generic type or method 'DbSet<TEntity>'. Nullability of type argument 'ChessTourManager.DataAccess.Entities.Tournament?' doesn't match 'class' constraint.

Converting null literal or possible null value to non-nullable type.

Possible null reference assignment.

Non-nullable field '_tournamentName' must contain a non-null value when exiting constructor. Consider declaring the field as nullable.

Dereference of a possibly null reference.

The type 'ChessTourManager.DataAccess.Entities.Tournament?' cannot be used as type parameter 'TEntity' in the generic type or method 'EntityFrameworkQueryableExtensions.Include<TEntity, TProperty>(IQueryable<TEntity>, Expression<Func<TEntity, TProperty>>)'. Nullability of type argument 'ChessTourManager.DataAccess.Entities.Tournament?' doesn't match 'class' constraint.

Dereference of a possibly null reference.

Nullability of reference types in type of parameter 't' of 'lambda expression' doesn't match the target delegate 'Func<Tournament?, Kind?>' (possibly because of nullability attributes).

The type 'ChessTourManager.DataAccess.Entities.Tournament?' cannot be used as type parameter 'TEntity' in the generic type or method 'EntityFrameworkQueryableExtensions.Include<TEntity, TProperty>(IQueryable<TEntity>, Expression<Func<TEntity, TProperty>>)'. Nullability of type argument 'ChessTourManager.DataAccess.Entities.Tournament?' doesn't match 'class' constraint.