The instance of entity type 'XXX' cannot be tracked because another instance with the same key value for {'Id'} is already being tracked

EF Core modification examples given: == ""

System.InvalidOperationException: The instance of entity type 'ProductInfo' cannot be tracked because another instance with the same key value for {'Id'} is already being tracked. When attaching existing entities, ensure that only one entity instance with a given key value is attached. Consider using 'DbContextOptionsBuilder.EnableSensitiveDataLogging' to see the conflicting key values.
 

Solution:

services.AddDbContext<DbContext, LTWMSDaoMysql.EFModel.LTWMSContext>(c=>c.UseMySQL(Configuration.GetConnectionString("mysqlcon")).UseQueryTrackingBehavior( QueryTrackingBehavior.NoTracking));