c# - Code First view number of keys -

c# - Code First view number of keys -

i trying utilize code first , database migration in mvc 5 project. in 1 of views have 20 keys

[key] [column(order = 19)] [stringlength(3)] public string useoftools { get; set; }

i error:

`the index '' on table "xxx" has 20 columns in key list. maximum limit index key column list 16`.

i appreciate suggestions.

c# sql-server asp.net-mvc ef-code-first