'IServiceCollection' does not contain a definition for 'Scan'

In a .NET Core App I’m facing this error:

Error	CS1061	'IServiceCollection' does not contain a definition for 'Scan' and no extension method 'Scan' accepting a first argument of type 'IServiceCollection' could be found (are you missing a using directive or an assembly reference?)

The code of ConfigureServices looks like this:

services.Scan(scan => scan
    .FromAssemblies(typeof(MaterialCommandHandler).GetTypeInfo().Assembly)
    .AddClasses(classes => classes.Where(x => {
        var allInterfaces = x.GetInterfaces();
        return
            allInterfaces.Any(y => y.GetTypeInfo().IsGenericType && y.GetTypeInfo().GetGenericTypeDefinition() == typeof(IHandler<>)) ||
            allInterfaces.Any(y => y.GetTypeInfo().IsGenericType && y.GetTypeInfo().GetGenericTypeDefinition() == typeof(ICancellableHandler<>));
    }))
    .AsSelf()
    .WithTransientLifetime()
);

I’m using Scrutor 2.0.0.