To upgrade an existing project that uses ver.3 or before to use ver.5 or later of this package:

1. Please confirm that the version of this package you use is ver.5 or later.

PM> Update-Package Toolbelt.EntityFrameworkCore.IndexAttribute

2. Remove using Toolbelt.ComponentModel.DataAnnotations.Schema;, and insert using Toolbelt.ComponentModel.DataAnnotations.Schema.V5; instead.

...
// 👇 Remove this line...
// using Toolbelt.ComponentModel.DataAnnotations.Schema;

// 👇 Insert this line, instead.
using Toolbelt.ComponentModel.DataAnnotations.Schema.V5;
...

3. Replace [Index] attribute to [IndexColumn] attribute.

...
public class Foo {
  ...
  // 👇 Replace [Index] to [IndexColumn]
  [IndexColumn] 
  public int Bar { get; set; }
  ...